Valves Sentence Examples

The valves are distinguished as dorsal and ventral.

The frui t is a pod or siliqua splitting by two valves from A "0 D FIG.

The two valves of the shell of the common cockle are similar to each other, and somewhat circular in outline.

These spiracles have firm chitinous edges, and can be closed by valves moved by special muscles.

The manufacture of springs, valves and washers does not require any very special notice, these articles being generally fashioned out of mixed rubber, and vulcanized either in moulds or in powdered French chalk.

This machine reproduces a copy of the original transmitting slip, which can be passed on to any other Wheatstone circuit or can be run through a " Creed printer," which is a pneumatic machine actuating a typewriter by means of valves.

In the Trimerellidae, for example, some of the muscles are attached to a massive or vaulted platform situated in the medio-longitudinal region of the posterior half or umbonal portion of both valves.

The function of this pair of muscles is the closing of the valves.

Two other pairs have been termed divaricators by Hancock, or cardinal muscles (" muscles diducteurs " of Gratiolet), and have for function the opening of the valves.

In the Testicardines, where no such sliding action of the valves was necessary or possible, no muscles for such an object were required, consequently none took rise from the lateral portions of the valves as in Lingula; but in an extinct group, the Trimerellidae, which seems to be somewhat intermediate in character between the Ecardines and Testicardines, have been found certain scars, which appear to have been produced by rudimentary lateral muscles, but it is doubtful (considering the shells are furnished with teeth, though but rudely developed) whether such muscles enabled the valves, as in Lingula, to move forward and backward upon each other.

By the contraction of the valves the small smooth seeds, which form FIG.

For high heads the water cylinders, valves and valve chambers are specially constructed to withstand heavy pressures, water being sometimes raised in a single lift to heights of more than 2000 ft.

Hydraulic pumping engines, while not differing essentially from steam pumps, must have specially designed valves in the power cylinder on account of the incompressibility of water.

The adjustment of the air currents in the different splits is affected by regulators which are placed in the return air-ways, and act as throttle valves to determine the volume of air in each case.

The simplest forms of pumps employed for forcing liquids are "plunger pumps," consisting essentially of a piston moving in a cylinder, provided with inlet and outlet pipes, together with certain valves.

The 'disposition of these valves divides this type of pump into suction pumps and force pumps.

E is a valve in the inlet pipe opening into the cylinder; and A the piston is perforated by one or more holes, each fitted with valves opening outwards on its upper surface.

In practice it may be considerably less, owing to leakage at the valves and between the piston and cylinder.

The cylinder, in which a well-fitting piston worked, was provided at its lower end with two valves.

This type of pump is, however, not very efficient, for there is not only leakage about the valves and between the piston and cylinder, but at a certain degree of exhaust the air within the vessel is insufficient to raise the inlet valve; this last defect has been met in some measure by using an extension of the piston to open and close the valve.

Neisen and others to introduce glass valves in lieu of stop-cocks.

Below each retort, and attached to it, is a cooler formed of thin sheet-iron, which receives the hot char as it passes from the retort, and at the bottom of the cooler is an arrangement of valves which permits a certain amount of char to drop out and no more.

The small ova are crowded beneath the dorsal part of the valves.

A very few have the power of swimming by opening and shutting the valves of the shell (Pecten, Lima); most can crawl slowly or burrow rapidly; others are, when adult, permanently fixed to stones or rocks either by the shell or the byssus.

The valves of the shell have been removed by severing their adhesions to the muscular areae h, i, k, 1, m, u.

In removing the valves of the shell from an Anodonta, it is necessary not only to cut through the muscular attachment of the body-wall 4 ?"

It is on this account that the valves of a dead Lamellibranch always gape; the elastic ligament is no longer counteracted by the effort of the adductors.

Whilst the valves of the shell are equal in Anodonta we find in many Lamellibranchs (Ostraea, Chama, Corbula, &c.) one valve larger, and the other smaller and sometimes flat, whilst the larger shell may be fixed to rock or to stones (Ostraea, &c.).

A further variation consists in the development of additional shelly plates upon the dorsal line between the two large valves (Pholadidae).

It is to be remembered that the whole of the cuticular hard product produced on the dorsal surface and on the mantle-flaps is to be regarded as the " shell," of which a median band-like area, the ligament, usually remains uncalcified, so as to result in the production of two valves united by the elastic ligament.

In Aspergillum the whole of the tubular mantle area secretes a continuous shelly tube, although in the young condition two valves were present.

This deficiency is very usual in the class; at the same time, many Lamellibranchs have tentacles on the edge of the mantle supplied by a pair of large well-developed nerves, which are given off from the cerebro-pleural ganglion-pair, A, When free swimming, shows the two dentigerous valves widely open.

The glochidium quits the gillpouch of its parent and swims by alternate opening and shutting of the valves of its shell, as do adult Pecten and Lima, trailing at the same time a long byssus thread.

Lima; members of this genus form a nest by means of the byssus, or swim by clapping the valves of the shell together.

Chamidae.-Shell with sub-equal valves and prominent umbones more or less spirally coiled; ligament external.

This has led to the loss of the radula, and is accompanied by the division of the shell into two valves.

Heat is regulated in the structures by means of valves on the various branch pipes.

The extinct Gryptochitonidae, Pilsbry, with other Palaeozoic genera, narrow and elongated in form with terminal margins of end valves elevated, belong to this group.

No shell-eyes, slits in the valves 1-7 corresponding with the ribs of the tegmentum.

Valves immersed in the girdle, with small tegmentum.

Vermiform, with thick girdle and small valves; insertion and sutural plates strongly drawn forward, sharp and smooth.

This appears to indicate that the Neomeniomorpha are descended from Chiton-like ancestors, and that they have lost their shell valves.

The next important step seems to have been taken in the 4th century when some forgotten Watt devised valves for the bellows.

The air and gas, the latter coming from the gas producers or other source, arrive through H and J respectively, and their path thence is determined by the position of the reversing valves K and K'.

In the position shown in solid lines, these valves deflect the air and gas into the left-hand pair of "regenerators" or spacious heat-transferring chambers.

The ovary is incompletely divided into many chambers by the ingrowth of the placentas which bear numerous ovules and form in the fruit a many-seeded short capsule opening by small valves below the upper edge.

The valves are hydroscopic, responding to increase in the amount of moisture in the atmosphere by closing the apertures.

In dry weather the valves open, and the small seeds are ejected through the pores when the capsule is shaken by the wind on its long stiff slender stalk.

The pollen is set free by the opening (dehiscence) of the anther, generally by means of longitudinal slits, but sometimes by pores, as in the heath family (Ericaceae), or by valves, as in the barberry.

The three valves bear the septa in the centre and the opening takes place through the back of the chambers.

The fruit is a capsule dehiscing by 5 sometimes io teeth or valves, or sometimes transversely (a pyxidium) as in Anagallis.

The valves of the giant clam (Tridachna) sometimes attain a length of 5 ft.

Without preheating the expanding air becomes so cold as to be liable to deposit snow from the moisture held in suspension, and thereby to clog the valves.

The forward-directed exopods either act as valves or form a tube (rarely two tubes), protensile and retractile, for regulating egress of water from the branchial regions.

The valves of the shell are closed by a single large adductor muscle, the anterior adductor being absent.

The two valves of the shell are unequal in size, and of different shape; the left valve is larger, thicker and more convex, and on it the animal rests in its natural state.

Starfishes devour large numbers; they are able to pull the valves of the shell apart and then to digest the body of the oyster by their everted stomach.

In the Cirripedia it forms a fleshy " mantle " strengthened by shelly plates or valves which may assume a very complex structure.

S presents a highly magnified section of one of the valves to show the successive moults.

B, Upper and filiform and fringed surface of same; valves closed.

The eggs are retained between the valves of the shell in some Phyllopoda and in the Cladocera and Ostracoda, and they lie in the mantle cavity in the Cirripedia.

The genital papilla of the female acquires a great development during the breeding season and becomes produced into a tube nearly as long as the fish itself; this acts as an ovipositor by means of which the comparatively few and large eggs (3 millimetres in diameter) are introduced through the gaping valves between the branchiae of pond mussels (Unio and Anodonta), where, after being inseminated, they undergo their development, the fry leaving their host about a month later.

Before the valves in the dam were closed, the village of Llanwddyn, the parish church, and many farmsteads were demolished.

All these various changes in the opening of the valves and dampers are automatically performed in the proper order by means of a hand-wheel H, the shaft m resting on the standards t and shaft v.

Alloys prepared in this way, and known as phosphor bronze, may contain only about 1% of phosphorus in the ingot, reduced to a mere trace after casting, but their value is nevertheless enhanced for purposes in which a hard strong metal is required, as for pump plungers, valves, the bushes of bearings, &c. Bronze again is improved by the presence of manganese in small quantity, and various grades of manganese bronze, in some of which there is little or no tin but a considerable percentage of zinc, are extensively used in mechanical engineering.

The suture is often towards one side in consequence of the valves being unequal.

The opening or dehiscence of the anthers to discharge their contents takes place either by clefts, by valves, or by pores.

Prorocentraceae (Schutt) (=the Adinida of Bergh); body surrounded by a firm shell of two valves without a girdle band; transverse groove absent; transverse flagellum coiled round base of longitudinal.

The cirripede, which has an elastic peduncle, a crested capitulum, but no valves, and the first cirrhi longer than the rest, should stand near Eremolepas, the name given by Weltner in place of the preoccupied Gymnolepas (Aurivillius).

Further, though the interchanger is still used by some makers, it has been found by experience that, with properly constructed valves and passages in the expansion cylinder, there is no trouble from the formation of snow, when, as is the general practice, the same air is used over and over again, the compressor taking its supply from the insulated room.

See our major project on air admittance valves for details of larger valves for toilets.

The options for eliminating risk of gland leakage is to use bellows sealed valves.

The valves of inarticulate brachiopods are held together by muscles without a hinge.

Two parallel vertical valves per cylinder are driven directly by a single overhead camshaft.

The principle of chain-driven camshafts below the valve plane and the operation of valves by means of tappets and rocker arms has been maintained.

Truma propane auto changeover valves Truma automatic changeover valves for propane bottles with left hand threaded connection.

Patients with prosthetic heart valves or who have had one previous episode of infective endocarditis should receive chemoprophylaxis according to the current UK recommendations.

The feed clack valves below the boiler give trouble by leaking.

High engine revs are allowed by a special valve retainer collet system used to secure the steel intake and exhuast valves.

Remove the inlet manifold and both heads, and inspect the piston crowns and valves for signs of heavy contact.

In its later life the high-pressure cylinder was replaced by a Corliss valve cylinder with all four valves at the top of the cylinder.

While the valves appear very delicate, the collagen in their structure makes them enormously strong.

The " dup " sound is caused by the closing of the aortic and pulmonary valves at the beginning of ventricular diastole.

To ensure better and more efficient dissipation of heat the outlet valves are filled with sodium.

They also have no valves valves and contain less elastic and muscle fibers more elastic and muscle fibers.

In the cookers, all the valves, from one to nine will be in single blocks incorporating the electronics.

A real trumpet is actually played by an artificial embouchure, the visitor controls air pressure and the valves and hears the results.

Once valves with indirectly heated filaments appeared things changed dramatically.

Install backflow valves or plugs on drains, toilets and other sewer connections to prevent floodwaters from entering your home.

Notable examples are hip joints, and replacement heart valves and vascular grafts.

Each cylinder has a unit injector fitted between the valves in the cylinder head.

This wattage had to include the power to heat the filaments of the valves, which took 2 kilowatts alone!

The recovered methanol will be cooled by the exhaust air from the pneumatic valves.

It had an oak, walnut or mahogany case, with a sloping front panel, and externally mounted valves.

Use of bovine pericardium allows production of valves and pericardial patches on a large scale with availability in all the necessary sizes.

Check for plumbing leaks, toilets that rock, corroded valves on the hot water heater and other plumbing leaks, toilets that rock, corroded valves on the hot water heater and other plumbing problems.

Dunlop was able, despite this, to patent his own design as it was a rubber pneumatic tire with a rim and valves.

The safety system is generally based on using high integrity safety relief valves.

Main drain off valves shall be located in service risers.

Stephenson's link motion, an Ashford type steam reverser and Ross pop safety valves were fitted.

Fitting of automatic fuel shut-off valves which are activated by the fire detection system should be considered.

As was customary at the time of construction, 1910, the HP side has piston valves whilst the LP side has slide valves.

Excluded were patients with mitral stenosis, artificial valves or heart transplant.

Guidance on the use and location of air valves in pipelines for both normal use and surge suppression is included.

The first sound is the simultaneous closure of the A/V valves, which is at the start of the ventricular systole.

The " lub " sound is caused by the closure of the AV valves at the beginning of atrial systole.

Two overhead camshafts operate (via bucket tappets) two 38mm intake and two 33mm outlet valves per cylinder.

All rooms have radiators with thermostatic radiator valves allowing you to adjust the temperature in each room.

Between 1941 and 1944 during the Second World War, a special purpose electronic computer using thermionic valves was developed by the British.

Patients being treated for AF will require lifelong therapy, as will those with prosthetic valves.

Cossart valve-gear Valve gear with four piston valves per cylinder operated by rotary cams.

The appropriate setting of the opening time of the solenoid valves presents a problem.

The non-return valves in the outlet of the adsorption dryer prevents full pressure equalization.

Normally their valves should allow blood to flow only inwards from the superficial veins to the deep veins.

When the ventricular pressure falls below the atrial pressure the AV valves open and blood begins to quickly fill the ventricles.

This causes the ventricles to contract forcing the blood to leave via the semi lunar valves to the arteries.

I always thought dump valves were those mods ppl put on to make that noise wen they change gear!

The right anterior corner of the right ventricle passes into the short stem, guarded by three semi-lunar valves, which divides into the two pulmonary arteries.

We have not only the observations of Semper and Morse, but the anatomical investigations of King, to confirm the sliding action or lateral divarication of the valves of Lingula.

With the fixed retorts these valves are worked from time to time by the attendant, but with revolving retorts they are worked continuously and automatically and allow from sixteen to twenty-four ounces of char to escape per minute from each cooler, and so make room in the retort above for a corresponding quantity to enter from the drying floor.

The principal industries are the manufacture of small arms (by the Colt's Patent Fire-Arms Manufacturing Co., makers of the Colt revolver and the Gatling gun), typewriters (Royal and Underwood), automobiles, bicycles, cyclometers, carriages and wagons, belting, cigars, harness, machinists' tools and instruments of precision, coil-piping, church organs, horse-shoe nails, electric equipment, machine screws, drop forgings, hydrants and valves, and engines and boilers.

Valves of the Shell of alimentary tract altogether, and must Cytherea (one of the Si be regarded as a special and peculiar palliate Isomya), from the development of the median anterior part pa dorsal aspect.

The state of closure of the valves of the shell is not, therefore, one of rest; when it is at rest - that is, when there is no muscular effort - the valves of a Lamellibranch are slightly gaping, and are closed by the action of the adductors when the animal is disturbed.

In the position shown in solid lines, these valves deflect the air and gas into the left-hand pair of " regenerators " or spacious heat-transferring chambers.

In the transmission of power by compressed air (see POWER TRANSMISSION) the air-driven motors are for the most part machines resembling steam-engines in the general features of their pistons, cylinders, valves and so forth.

He loves to climb the bed-posts and unscrew the steam valves much better than to spell, but that is because he does not understand that words would help him to make new and interesting discoveries.

Chrome radiator valves can be purchased at the bottom of the page or you can choose from a wider range by clicking here.

Prosthetic heart valves introduced to patients with rheumatic heart disease to lessen the risk for embolic stroke.

Stephenson 's link motion, an Ashford type steam reverser and Ross pop safety valves were fitted.

As the semilunar valves close a sound like the word ' dup ' can be heard and this is called the second heart sound.

Very accurate motion controls are possible using sophisticated servo valves.

Use a stethoscope to listen to the sound of the heart valves closing.

We also manufacture market-leading plastic flushing siphons, flushing and inlet valves, in-wall frames and supports, spares and accessories.

The control system acts through firing angle adjustments of the thyristor valves and through tap changer adjustments on the converter transformers.

B. Venous valves are folds of tissue formed from the endothelial lining of the tunica intima.

To maintain unidirectional flow the large veins have a series of valves.

Know where your stop valves are and ensure that they work so that you can turn off your water supply in an emergency.

I always thought dump valves were those mods ppl put on to make that noise wen they change gear !

On TDC with valves supposedly closed air is whooshing out of the inlet manifold.

The spill-proof valves protect your child's clothing as well as upholstered furniture.

Valves should not be so loose, however, that they fall out completely.

It comfortably seats or sleeps two people and features quick-inflating valves.

If you're in a hurry and need to remove the bottles from the water station before they are full, the docking station's valves prevent leaks - so no spills!

There are small spray valves set up in a 360 degree rotation, making full body application possible.

People who use heroin may also develop infections in the lining of the heart or its valves.

Create a physical access to get to valves and pipes.

Always leave 24 inches or more of floor space directly in front of the toilet, keep access to water shutoff valves clear, and keep access to tubs and showers easy to maneuver in and out of.

Turn off the hot and cold water supply valves located underneath the sink.

Turn the faucet on to make sure no water comes out and the valves are completely shut.

Remove the old Teflon tape from the threaded nipples on the hot and cold water valves and replace it with a fresh wrap of the Teflon tape.

Clean up any residual plumber's putty that may have squeezed out from underneath the Pegasus kitchen faucet and turn the hot and cold water valves back on.

Similarly, do not over-tighten the water supply hose connections on the shut-off valves.

Your gas and electric meters should also be kept free from ice and snow during the winter, and shut-off valves should be easily accessible.

Keep turning on all valves, including the toilet and shower, until antifreeze flows out, and close them.

Finally, LP gas systems include tanks, hoses, regulators and valves.

During the echo, an ultrasound transducer (hand-held wand placed on the skin of the chest) emits high-frequency sound waves to produce pictures of the heart's valves and chambers.

A heart murmur is an abnormal swishing or whooshing sound made by blood moving through the heart, heart valves, or blood vessels near the heart during the heartbeat cycle.

When the heart beats, normally it makes two sounds, "lubb" when the valves between the atria and ventricles close, and "dupp" or "dub" when the valves between the ventricles and the major arteries close.

The characteristics of the murmur may suggest specific alterations in the heart or its valves.

Innocent heart murmurs are caused by blood flowing faster than normal through the chambers and valves of the heart or the blood vessels near the heart.

These include defective heart valves, hypertrophic cardiomyopathy (enlarged heart muscle), holes or abnormal openings in the walls of the heart (septal defects), aortic aneurysm, or other congenital heart disease.

Valves that are narrow, tight, or stiff (valvular stenosis) do not open completely and limit the forward flow of blood through the valve.

Valves that do not close properly may cause blood to leak back through the valve (called valve regurgitation).

Bacterial endocarditis (an infection of the heart) or rheumatic fever can damage heart valves or other structures of the heart and lead to heart murmurs.

Valve replacement or valve repair surgery are two treatment options for severely damaged or diseased valves.

It ususally occurs among school-aged children and cause serious damage to the heart valves.

The FHR is picked up by means of an ultrasound transducer and the movement of the heart valves.

Rheumatic fever causes inflammation of the heart and damage to the heart valves.

Between 75 and 85% of children with Marfan have loose or "floppy" mitral valves, which are the valves that separate the chambers of the heart.

When these valves do not cover the opening between the chambers completely, the condition is called mitral valve prolapse.

When heart valves, arteries, or veins are narrowed, they partially or completely block the flow of blood.

Stenosis is a narrowing of the valves or arteries.

Atrioventricular canal defect (also called endocardial cushion defect or atrioventricular septal defect) is a large hole in the septum, accompanied by abnormal tricuspid and mitral valves that are not formed as individual valves.

Catheter-based procedures may be performed to open stenotic valves or vessels, widen the septal opening between the atria, or close abnormal vessels or certain septal defects.

Blood vessel blockages or stenotic valves may be treated during the catheterization procedure using a specialized balloon tip or other device at the end of the catheter.

Rheumatic fever can seriously damage the valves of the heart.

The valves within the heart (structures that allow the blood to flow only in the correct direction and only at the correct time in the heart's pumping cycle) are frequently damaged during the course of pancarditis.

Endocarditis-Inflammation of the inner membrane lining heart and/or of the heart valves caused by infection.

As many as 15 percent of children with Turner syndrome have bicuspid aortic valves, where the major blood vessel from the heart has only two rather than three components to the valve regulating blood flow.

Bicuspid aortic valves can deteriorate or become infected, so it is advised that all girls with Turner syndrome undergo annual cardiac evaluations.

Endocarditis-Inflammation of the inner membrane lining of the heart and/or of the heart valves caused by infection.

Rheumatic fever can cause permanent damage to the heart and heart valves.

In others there may be permanent damage to the heart and heart valves.

In addition, these anomalies make the lining of the heart more susceptible to infection (endocarditis), which can damage valves and lead to blood poisoning (septicemia).

Some models have temperature valves at the top.

The warranty excludes gaskets, knobs, valves and pumps, unless the consumer proves these pieces were defective at purchase.

Among the technological characteristics of these Blancpain watch models are antimagnetic cases, decompression valves, unidirectional bezels, power reserve indicators, and rotating bezels.

A vibration that gets worse at higher engine speeds can mean a problem with your spark plugs, fuel injector, or engine valves.

To regulate the heat it is necessary either to instal a number of small radiators or to divide the radiators into sections, each section controlled by distinct valves; steam may then be admitted to all the sections of the radiator or to any less number of sections as desired.

In the ordinary working of a hot-water apparatus the expansion pipe already referred to will prevent any overdue pressure occurring in the boiler; should, however, the pipes Safety become blocked in any way while the apparatus is valves.

It receives the three great venous trunks of the body, namely the vena cava superior dextra, the vena cava superior sinistra more dorsally, and the vena cava inferior more to the right and below; the opening of the last is guarded by two prominent valves in place of the mammalian valvula Eustachii.

The blood leaves the heart past three semi-lunar valves, by the right aorta, this being alone functional, a feature characteristic of, and peculiar to, birds.

All types of valves are with few exceptions operated by a link motion, generally of the Stephenson type, occasionally of the Allan type or the Gooch type, or with some form of radial gear as the Joy gear or the Walschaert gear, though the latter gear has characteristics which ally it with the link motions.

Generally steam from the boiler is admitted direct to the low-pressure cylinder through a reducing valve, and valves and devices are used to prevent the steam so admitted acting as a back pressure on the high-pressure cylinder.

The fruit is a capsule splitting generally by three longitudinal slits forming valves which remain united above and below.

The seeds are minute and innumerable; they contain a small rudimentary embryo surrounded by a thin loose membraneous coat, and are scattered by means of hygroscopic hairs on the inside of the valves which by their movements jerk out the seeds.

The main trunks of the vascular system often possess valves at the origin of branches which regulate the direction of the blood flow.

The soft body of the Brachiopod is in all cases protected by a shell composed of two distinct valves; these valves are always, except in cases of malformation, equal-sided, but not equivalved.

The valves are, consequently, essentially symmetrical, which is not the case with the Lamellibranchiata, - so much so, that certain Brachiopod shells were named Lampades, or lamp shells, by some early naturalists; but while such may bear a kind of resemblance to an antique Etruscan lamp, by far the larger number in no way resemble one.

The valves are also in some species very unequal in their respective thickness, as may be seen in Productus (Daviesiella) 1 llangollensis, Davidsonia verneuilii, &c., and while the space allotted to the animal is very great in many species, as in Terebratula sphaeroidalis, it is very small in others belonging to Stro phomena, Leptaena, Chonetes, &c. The ventral valve is usually the thickest, and in some forms is six or seven times as great as the opposite one.

On the inner surface of both valves several well-defined muscular, vascular and ovarian impressions are observable; they form either indentations of greater or less size and depth, or occur as variously shaped projections.

The ventral valve in many of the genera is provided with two curved hinge-teeth, which fit into corresponding sockets in the opposite valve, so that the valves cannot be separated without breaking one of the teeth.

Hancock, Gratiolet and others to be connected with the opening and closing of the valves, or with their attachment to or movements upon the peduncle.

Owing to the strong and tight interlocking of the valves by the means of curved teeth FIGS.

The central and umbonal muscles effect the direct opening and closing of the shell, the laterals enable the valves to move forward and backward on each other, and the transmedians allow the similar extremities (the rostral) of the valves to turn from each other to the right or the left on an axis subcentrically situated, that is, the medio-transverse region of the dorsal valve.

They mention that it is never done suddenly or by jerks, as the valves are at first always pushed to one side several times and back again on each other, at the same time opening gradually in the transverse direction till they rest opposite to one another and widely apart.

Those who have not seen the animal in life, or who did not believe in the possibility of the valves crossing each other with a slight obliquity, would not consent to appropriating any of its muscles to that purpose, and consequently attributed to all the lateral muscles the simple function of keeping the valves in an opposite position, or holding them adjusted.

Crania in life opens its valves by moving upon the straight hinge, without sliding the valve.

Pro-deltidium attached to dorsal valves.

The pedicle passes out at right angles to the plane of junction of the valves of the shell; the opening is confined to the ventral valve, and may take the form of a slit, or may be closed by the development of a special plate called the listrium, or by a pseudo-deltidium.

When ripe the two carpels separate in the form of two valves and liberate a large number of seeds, each provided at the base with a tuft of silky hairs, and containing a straight embryo without any investing albumen.

The older, devised by Hooke in 1667, is provided with valves above and below, both opening upward, through which the water passes freely during descent, but which are closed by some device on hauling up. The newer or slip water-bottle type consists of a cylinder allowed to drop on to a base-plate when a sample is tro be collected.

A great future was expected from its use in the liquid state, since a cylinder fitted with the necessary reducing valves would supply the gas to light a house for a considerable period, the liquid occupying about T h.

They have the valves broad at both ends, and were placed by Sars in a separate tribe, called Platycopa.

By various modifications of their valves and appendages the creatures have become adapted for swimming, creeping, burrowing, or climbing, some of them combining two or more of these activities, for which their structure seems at the first glance little adapted.

Considering the imprisonment of the ostracod body within the valves, it is more surprising that the Asteropidae and Cypridinidae should have a pair of compound and sometimes large eyes, in addition to the e median organ at the base of I the " frontal tentacle," than 6 that other members of the group should be limited to P that median organ of sight, or have no eyes at all.

As might be expected, in thickened and highly embossed valves thin spaces occur over the visual organ.

The young, though born with valves, have at first a nauplian body, and pass through various stages to maturity.

After a few days, when the mantle bearing the shell valves has developed so much as to enclose the whole body, the young cockle sinks to the bottom and commences to follow the habits of the adult..

The discharge at the weir whilst it is raised is effected either by partially tipping some of the shutters by chains from a foot-bridge, or by opening butterfly valves resembling small shutters in the upper panels of the shutters.

The Lamellibranchia are mainly characterized by the rudimentary condition of the head, and the retention of the primitive bilateral symmetry, the latter feature being accentuated by the lateral compression of the body and the development of the shell as two bilaterally symmetrical plates or valves covering each one side of the animal.

The chief points in which they vary are - (1) in the structure of the ctenidia or branchial plates; (2) in the presence of one or of two chief muscles, the fibres of which run across the animal's body from one valve of the shell to the other (adductors); (3) in the greater or less elaboration of the posterior portion of the mantle-skirt so as to form a pair of tubes, by one of which water is introduced into the sub-pallial chamber, whilst by the other it is expelled; (4) in the perfect or deficient symmetry of the two valves of the shell and the connected soft parts, as compared with one another; (5) in the development of the foot as a disk-like crawling organ (Arca, Nucula, Pectunculus, Trigonia, Lepton, Galeomma), as a simple plough-like or tongueshaped organ (Unionidae, &c.), as a re-curved saltatory organ (Cardium, &c.), as a long burrowing cylinder (Solenidae, &c.), or its partial (Mytilacea) or even complete abortion (Ostraeacea).

The mantle-skirt is always long, and hides the rest of the animal from view, its dependent margins meeting in the middle line below the ventral surface when the animal is retracted; it is, as it were, slit in the median line before and behind so as to form two flaps, a right and a left; on these the right and the left calcareous valves of the shell are borne respectively, connected by an uncalcified part of the shell called the ligament.

I see only a coincidence of occurrences such as happens with all the phenomena of life, and I see that however much and however carefully I observe the hands of the watch, and the valves and wheels of the engine, and the oak, I shall not discover the cause of the bells ringing, the engine moving, or of the winds of spring.