Heider bryonic membranes are vestigial or entirely wanting.
Tail vestigial or absent.
The alimentary canal, which may be represented by a vestigial structure, is accordingly not functional, and the larva does not become pelagic. A pyriform organ is present in most Gymnolaemata as well as the sucker by which fixation is effected.
In some Psocidae the wings are in a vestigial state, and the fully winged species rarely if ever fly.
In the Malacostraca it is absent in the adult, or persists only in a vestigial condition, as in some Decapoda and Schizopoda.
17, C, a); he suggests they may represent vestigial structures pointing back to some ancestral form beyond the limits of the present group. The Gnetales probably had a separate origin from the other Gymnosperms; they carry us nearer to the Angiosperms, but we have as yet no satisfactory evidence that they represent a stage in the direct line of Angiospermic evolution.
Hallux vestigial or absent since Oligocene.
In the male of Phyllodromia the rudiment of a vestigial ovary becomes separated from the developing testis, indicating perhaps an originally hermaphrodite condition.
The extreme of this " division of labour " is seen, in those insects whose jaws are vestigial in the winged state, when, the need for feeding all behind them, they have but to pair, to lay eggs and to die.
Biting mandibles; vestigial maxillulae; second maxillae incompletely fused.
Maxillulae vestigial or absent.
Mandibles present in pupa, vestigial in imago; maxillae suctorial without specialization; first maxillae with lacinia, galea and palp. Prothorax small.
Mandibles absent in imago, very exceptionally present in pupa; first maxillae nearly always without laciniae and often without palps, or only with vestigial palps, their galeae elongated and grooved inwardly so as to form a sucking trunk.
But the vestigial jaws, numerous Malpighian tubes, and specialized wings of may-flies forbid us to consider the order as on the whole primitive.
The Corrodentia retain vestigial maxillulae and two pairs of Malpighian tubes, but the wings are somewhat specialized in the Copeognatha and absent in the degraded and parasitic Mallophaga.
It seems likely that the coelomic pore-canals were originally excretory organs, but in the existing Enteropneusta the pore-canals (especially the collar canals) have, as we have seen, acquired new functions or become vestigial, and the function of excretion is now mainly accomplished by a structure peculiar to the Enteropneusta called the glomerulus, a vascular complex placed on either side of the anterior portion of the stomochord, projecting into the proboscis-coelom.
Cope (Proc. Ac. Philad., 1864, p. 230) resorted to the modifications of the squamosal, ectoand endopterygoid bones, the condition of the vestigial limbs, and the teeth:- Scolecophidia (Typhlopidae), Catodonta (Glauconiidae), Tortricina (Ilysiidae and' Uropeltidae), Asinea, Proteroglypha and Solenoglypha.
Eyes vestigial or hidden; lower jaw toothless; without enlarged ventral scales: Typhlopidae.
Eyes vestigial; teeth restricted to the lower jaw; without en- larged ventral scales: Glauconiidae.
Vestigial palps have been described in various species of Hemiptera, but the true nature of these structures is doubtful.
A, Female from above; d, Jaws, more highly magnified b, From beneath, magnified 5 (tips of mandibles and 1st times; maxillae still more highly c, Vestigial wing; magnified).
The feelers are long and simple, and the wings are very narrow, each with a sub-costal, a radial, a median and a cubital nervure; the branches of the median and the cubital, however, as well as the anal nervures, are vestigial, and there are a few short cross-bars between After Marlatt, Ent.
In the absence of cerci the Corrodentia are more specialized than the Isoptera and Plecoptera, but some of them show a more primitive character in the retention of vestigial maxillulae - the minute pair of jaws that are found behind the mandibles in the Aptera.
On the other hand, the reduced feelers, the numerous Malpighian tubes (40), the large complex eyes, the vestigial condition of the jaws, the excessive size of the fore-wings as compared with the hind-wings and their complex neuration with an enormous number of crossnervules are all specializations.
Are absent or vestigial in all other insects; and, in most genera, by the presence in the adult of abdominalappendagesused for locomotion, these latter varying in number from one to nine pairs.
In the parasitic Rhizocephala and in a few Copepoda (Monstrillidae) the alimentary canal is absent or vestigial throughout life.
Development shows that the glandular tube is mesoblastic in origin and is of the nature of a coelomoduct, while the end-sac is to be regarded as a vestigial portion of the coelom.
It has been suggested that the above-mentioned callosities or " chestnuts " on the limbs of horses are vestigial scent-glands; and it is noteworthy that scrapings or shavings from their surface have a powerful attraction for other horses, and are also used by poachers and burglars to keep dogs silent.
The anterior antennae are fused with the anchoring attachment, whilst the posterior pair is vestigial, and the appendages of the mouth and body present various degrees of degeneration and specialization.
It is urged that the imperfect placenta of the bandicoots instead of being vestigial, may be an instance of parallelism, and that in marsupials generally the allantois failed to form a placental connexion.
Finally, there is the hypothesis that marsupials are the descendants of placentals, in which case, as was suggested by its discoverer, the placenta of the bandicoots would be a true vestigial structure.
In the ostrich and in the Amazon parrots, which are vestigial feathers without barbs.
With large crop, vestigial caeca.
It is regarded as a modified zooecium, the polypide of which has become vestigial, although it is commonly represented by a sense-organ, bearing tactile hairs, situated on what may be termed the palate.
O or vestigial hindlimbs.
