Sirian partnered with Rissa while the guards fanned out around them, one alert while the other four paired up to spar.
The collarcavity (b.c. 2) is paired, although its ventral mesentery is not complete.
Uzel, with the majority of students, regards the paired organs as mandibles and the unpaired as an epipharynx.
Hinds believe that the paired piercers are the inner lobes of the maxillae, and the unpaired piercer the left mandible, the right mandible being absent.
He therefore regards it as the inner lobe (lacinia) of that maxilla, comparing it with the remarkable " pick " of the maxilla of a book-louse (see Copeognatha in article Neuroptera), The paired piercers, connected by muscles with the base of the maxillae, but attached directly to the head skeleton, into which they can be withdrawn, are regarded by Borner as true mandibles.
In the Aglossal Xenopus, the tadpoles are likewise devoid of circular lip, horny teeth, and beak, and they are further remarkable in the following respects: There is a long tentacle or barbel on each side of the mouth, which appears to represent the "balancer" of Urodele larvae; the spiraculum is paired, one on each side; the fore limbs develop externally, like the hind limbs.
There are two main theories: (I) that the chromosomes which finally separate are at first paired side by side (Allen, Grgoire, Berghs, Strasburger and others), and (2) that they are joined together or paired end to end (Farmer and Moore, Gregory, Mottier and others).
(3) The os entoglossum originally paired, but coalescing into an arrow-headed piece, attached to the anterior end of the basihyal and lodged in the tongue proper.
Sometimes the ventral portions of these pads form paired or un paired little ossifications, then generally described as intercentra; such are not uncommon on the tail.
Dorsal vertebrae frequently have a ventral outgrowth of the centrum; these hypapophyses may be simple vertical blades, I-shaped, or paired knobs; they serve for the attachment of the thoracic origin of the longus collianticus muscle, reaching their greatest development in Sphenisci and Colymbidae.
Omitting the paired tracheo-clavicular muscles, we restrict ourselves to the syringeal proper, those which extend between tracheal and bronchial rings.
The ventral region of the thoracic skeleton is complex, each segment usually possessing a median sternum with paired episterna (in front) and epimera (behind).
The well-known "fire-flies" of the tropics are large click-beetles (Elateridae), that emit light from paired spots on the prothorax and from the base of the ventral abdominal region.
Short cerci, and the Pelobiidae, which have elongate larvae, tapering to the tail end, where are long paired cerci and a median process, recalling the grub of a Mayfly.
9, c) is slender with elongate legs, and the abdominal segments carry paired tracheal gills.
After eating the contents of the egg, the larva moults and becomes a fleshy grub with short legs and with paired spiracles close to the dorsal region, so that, as it floats in and devours the honey, it obtains a supply of air.
Biisgen that the sweet secretion (honey-dew) of the aphids is not derived, as generally believed, from the paired cornicles on the fifth abdominal segment, but from the intestine, whence it exudes in drops and is swallowed by the ants.
Commonly the nephridia are strictly paired a single pair to each segment, while the branches of the blood vascular system are similarly metameric. The alimentary canal is nearly always a straight tube running from the mouth, which is surrounded by the first segment of the body and overhung by the prostomium, to the anus,which is then either surrounded by the last segment of the body or opens dorsally a little way in front of this.
In any case the cavity of the prostomium is single, and not formed, as is the cavity of the segments of the body, by paired coelomic chambers.
Among the simpler Chaetopoda the coelom retains the character of a series of paired chambers, showing the above relations to the exterior and to the gonads.
Though the paired arrangement of the nephridia is the prevalent one in the Chaetopoda, there are many examples, among the Oligochaeta, of species and genera in which there are several, even many, nephridia in each segment of the body, which may or may not be connected among themselves, but have in any case separate orifices on to the exterior.
Tomopteris is remarkable for the fact that the hammer-shaped prostomium has paired ventral processes each with a single seta.
In this worm the paired nephridia exist in most of the segments of the body, and their form (see fig.
Nephridia generally paired, often very numerous in each segment, in the form of long, much-coiled tubes with intracellular lumen.
Generative pores usually paired, sometimes single and median.
It has been shown (Bourne) that the "perichaetous" condition is probably secondary, inasmuch as in worms which are, when adult, "perichaetous" the setae develop in pairs so that the embryo passes through a stage in which it has four bundles of setae, two to each bundle, the prevalent condition in the group. Rarely there is an irregular disposition of the setae which are not paired, though the total number is eight to a segment (fig.