The upper surface of the elytron is sharply folded inwards at intervals, so as to give rise to a regular series of external longitudinal furrows (striae) and to form a set of supports between the two chitinous layers forming the elytron.
The corolla is generally funnelshaped, more rarely bell-shaped or tubular; the outer face is often marked out in longitudinal areas, five well-defined areas tapering from base to apex, and marked with longitudinal striae corresponding to the middle of the petals, and alternating with five non-striated weaker triangular areas; in the bud the latter are folded inwards, the stronger areas being exposed and showing a twist to the right.
Later, in his article " Chromatics " in the supplement to the 5th edition of this encyclopaedia, he shows that the colours " lose the mixed character of periodical colours, and resemble much more the ordinary prismatic spectrum, with intervals completely dark interposed," and explains it by the consideration that any phasedifference which may arise at neighbouring striae is multiplied in proportion to the total number of striae.
The direction of striae on the underlying quartzitic rocks, particularly well seen near the Douglas colliery, Balmoral, point to an ice movement from the north-north-west to south-south-east.
With the exception of the heavier flint (lead) glasses, these can be produced so as to be free both from noticeable colour and from such defects as bubbles, opaque inclusions or " striae," but extreme care in the choice of all the raw materials and in all the manipulations is required to ensure this result.
While such minute and gradual variations are harmless for most optical purposes, sudden variations which generally take the form of striae or veins are fatal defects in all optical glass.
In their coarsest forms such striae are readily visible to the unaided eye, but finer ones escape detection unless special means are taken for rendering them visible; such special means conveniently take the form of an apparatus for examining the glass in a beam of parallel light, when the striae scatter the light and appear as either dark or bright lines according to the position of the eye.
Plate glass of the usual quality, which appears to be perfectly homogeneous when looked at in the ordinary way, is seen to be a mass of fine striae, when a considerable thickness is examined in parallel light.
Plate glass is, nevertheless, considerably used for the cheaper forms of lenses, where the scattering of the light and loss of definition arising from these fine striae is not readily recognized.
The examination of small test-pieces of the glass withdrawn from the crucible by means of an iron rod having shown that the molten mass is free from bubbles, the stirring process may be begun, the object of this manipulation being to render the glass as homogeneous as possible and to secure the absence of veins or striae in the product.
To make a really good mirror of glass two things are required - a plate free from bubbles and striae, and a method of applying a film of metal with a uniform bright surface free from defects.
Glacial furrows, striae and elongated troughs are met with everywhere, running mostly from north-west to south-east, as well as asar or eskers, which have the same direction.
The crumpled bands mark the bedding, and the fine perpendicular striae in front are the cleavage planes; the fine lines on the darkened side merely represent shadow, and must not be taken for planes of division in the rock.
Sprats are very often confounded with young herrings, which they much resemble, but can always be distinguished by the following characters: they do not possess any teeth on the palate (vomer), like herrings; their gill-covers are smooth, without the radiating striae which are found in the shad and the pilchard; the anal fin consists of .from seventeen to twenty rays, and the lateral line of forty-seven or forty-eight scales.
High, half a mile or a mile long, with axes parallel to the direction of the ice motion as indicated by striae on the underlying rock floor; these hills are known by the Irish name, drumlins, used for similar hills in north-western Ireland.
Crassatellidae.-Shell thick, with concentric striae, ligament external; foot short.
I), the striae on each face being therefore at right angles to those of the adjoining faces, and indicating an oscillatory combination of the cube and pentagonal dodecahedron.
The Glacial striae, and the dislocated rocks - moved a few inches or feet from their places, and others, at greater distances, turned over, and beginning to assume the sub-angular form of Glacial boulders - were found precisely as the glacier, receding from the bar, and giving place to the ancient lake, had left them, covered and preserved by sand and gravel washed from the terminal morain.
All the large disks were crossed by striae, or were otherwise deficient in the necessary homogeneity and purity.
Consequently, for a certain focal length, much deeper curves must be resorted to if the new glasses are to be employed; this means not only greater difficulties in workmanship, but also greater thickness of glass, which militates against the chance of obtaining large disks quite free from striae and perfect in their state of annealing.
Or more - was pushed along by ice radiating from different centres, evidence of which is to be seen in the direction of the striae on the rocky surface of the country as well as in the dispersion of boulders and stones from recognizable districts.
Glacial deposits spread over the lower grounds and striae occur at great heights on the Black Mountains.