Below there is only a single sphenoid bone, which is oblong. Two large triangular bones, which are manifestly analogous to those named corners by envier in the frogs, form the flooring of the nostrils below, and give off each a slender apophysis, which extends backwards under the sphenoid parallel to its correspondent. It is to these bones and to their apophyses that the two longitudinal rows of the palatal teeth of the Salamanders adhere. Between the anterior part of these bones, behind the intermaxillaries, is a large oval apace, which is filled by the membrane of the palate only ; their posterior and dentary apophysis extends nearly as far backwards as tho ephenoid bone. Perhaps, observes Cuvier, it is divided at certain periods into two by a suture, and a palatine bouo may then be distinguished, but he had not been able to perceive one. There is in the orbit,.at its anterior wall, n great membranous apace between the maxillary bone, the anterior frontal, and the vomer ; and it is at the bottom of this space, and in a notch of the corner, that the internal nostril is pierced on each side. The bottom of the orbit, on the side of the cranium, between the frontal and parietal bones on one side, and the comer and sphenoidal bones on the other, is occupied by an oblong bone in which the optic hole is pierced, and which can only answer to the orbital wing of the sphenoidal bone. It is this part which is membranous in the frogs, and has no existence in the serpents, in which the parietal and frontal bones each supply it by halves ; here it is elevated to tho state of a particular bone. The two occipital condyles are very much separated from each other, and placed at the two sides of the occipital bole.
The cranium of the European Aquatic Salamanders differs in general from that of the Terrestrial in having the entire head more oblong, the external nostrils more npproximated, the space between the comers a simple small hole, the pterygoid bone a mere plate, wide behind and pointed before, &c. They also differ among themselves.
The os hyoldes is subject to changes in the Salamanders, as in the frog. in its larva state it has two hyoelian branches springing from the occipital bones, uniting forwards under the lower jaw, and n cartila ginous branchial apparatus suspended at the point of union of those branches, and supporting four arches on each side, the first of which is attached to an intermediate stem, the three following to a second two jointed stem, and these two pairs of stems to an unequal branch, as is more clearly manifested in the Axolotl. The adult Aquatic Salamanders preserve in the bony state the branches which still are attached below the fenestra malls, and terminate forward by a truncation under the middle of the lower jaw ; but the anterior articulation of these branches is now become membranous. The unequal stem, in the bony state, supports on each side an osseous branch consisting of two joints, terminated by a cartilaginous point, and moreover, internally, another branch which is simple and reduced to a filament, which goes from the unequal stem to the second articulation of the external branch. In the Terrestrial Salamander, which can only pass a very short time in the larva state, all remains cartilaginous. The two suspensive branches or anterior horns are delicate and flat, and do not join the cranium ; and the unequal stern with its two branches soldered on each aide by their two ends, forma only a single chevron-shaped cartilage, each brimeli of which is pierced with a considerable gap. This remainder or vestige of the branchial apparatus does not prevent the co-existence of a larynx and the rudiment of a sternum ; both indeed weak and membranous rather than cartilaginous. The shoulder of the Salamander is very curious on account of the close junction of its three bones into a single one, which has the glenoid fosset at its anterior edge, sends towards the spine a square lobo slightly enlarged above, which is the oinoplate, and towards the brcaat n rounded disk, slightly lobated, which is composed of the clavicle and eoracobl bone, where a suture which separates them may for n long time be observed, and where there always remains small hole. The oinoplate has its spinal edge augmented by a cartila ginous prolongation. The cleido-coracoid is also surrounded with a great cartilaginous blade in form of a crescent, which crosses upon its congener under the breast; for the only vestige of a sternum remaining is a cartilaginous blade placed behind the two preceding, and which represents the xiphold. The atlas of the Salamander is articulated with the head by tweeconcave facets, and with the second vertebra IT the face of its body, which is also concave ; for, contrary to the case of the frogs and lizards, all the anterior faces of the bodies of the vertebrae are convex in the Saliunandene and all the posterior faces concave ; the upper part is fiat. The articular apophyses are horizontal, and united on each aide by a crest, which, joined to that of the other side, gives to the vertebra a sort of roof which is rectangular, but with its lateral borders a little re-entering. The posterior parts of a vertebra
lie on the anterior parts of that which follows it. In lieu of spinoua apophyses, there is only a slight appearance of a longitudinal ridge. The body of the vertebra, which is cylindrical end narrowed in its middle, adheres wider the roof above noticed. The transverse apophyses also adhere under the lateral crests, are directed slightly backwards, and divided by a furrow on each of their faces, so that their extremity has as it were two tubercles for carrying those into which the base of the small rib is divided. These small ribs adjoin all the cervical, dorsal, and lumber vertebrre, except the atlas, but are only two or three lines in length, and are far from surrounding the trunk or reaching the sternum. Among the Aquatic Salamanders, the Triton Gerneri has the crest of the dorsal vertebra more elevatodand sharp than the Terrestrial Salamander; this crest is also rather more developed in Triton alprstris, and even in Triton punctatus and Triton palmatus ; but what, adds Cuvier, is very singular, it is precisely in Triton criatat as that this crest is most effaced, and the upper part of the vertebra nearly plain. The vertebrae of the tail (25 or 26 in number) in the Terrestrial Salamander have crests and transverse epophyses like those of the heck ; they become smaller and smaller, and, counting from the third caudal, there is under the body a transverse blade directed obliquely backward., pierced. with a hole at its base, which represents the chevron- ones of the lizards and the other long-tailed genera.. Cuvier counted 33 caudal vertebra in the Triton alpestris and Triton cristatus, 34 in Triton Grsneri, and 36 in Triton punctatus. They form, he observes, a tail flattened laterally, in consequence of the elevation of their tipper and lower crests. The bones of the limbs are, says Cuvier in continuation, proportioned to the smallness of the inembereh I teemse.ves. The humerus hart, above, a round head ; a little lower, forwards, there is a compressed and obtuse tuberosity; and backwards, n little lower still, another very pointed one. Its lower head is flattened from before backwards, and widened to suit the condyles, between which is an auricular bead, rounded for the forearm, and above, forwards, a small tweet. The Aquatic Sala mander has this bone more widened above than the Terrestrial species. The fore-arm is composed of two separate bones. The radius has round upper head, a narrowed body, and a compressed and widened lower head. The cubit is more equal in size, and its olecranou is very short and rounded. The carpus has 5 bones and 2 cartilages which occupy the place of bones, 7 pieces in all : the whole of these are flat, angular, disposed in a pavement-like order, and in some respects announce the structure to be seen in the Ictliyosaures. in the first rank are two, of which the smallest or radial is cartilaginous. The greatest belongs to the radius and ulna; between them on the second rank is a single one ; then come, on the third rank, four for the meta carpals The first remains cartilaginous. The metacarpals are short, flat, and narrowed in their middle. Cuvier found only one phalanx °Reified on the find finger, two on the eecond and fourth, and three on the third. The variety of points by which the pelvis is attached to the spine is, he remarks, n very singular thing. lie had individuals of the Terrestrial Salamander in which it was suspended from time 15th vertebra (counting in the atlas), and others in which it was suspended from the 16th; and he refers to a specimen (species undetermined) seen by 31. Schultze, in which it was suspended on One side to the 16th vertebra, and on tho other to the 17th. With regard to the Aquatic Sahunanders, Curler found it constantly suspended to the 14th in Triton palmatus and Triton alprstris, to the 15th in Triton punctatus and Triton Ganeri, and to tho pith or 1Sth in Triton crigattls. lie Lind an individual of the last-named species, in which it was suspended on One side to the 17th vertebra, and on the other to the 18.th. Tho pelvis itself is quite differently formed from that of the frogs. Time vertebra which supports it is like those which precede it, and has, like them, on each aide a email rib, at the extremity of which the ea ilii is suspended by a ligament. It is cylindrical, and widens a little on arriving at the cotyloid cavity. The pubis and ischium are soldered together, and form, with those of the other side, from which they are distinct, a large disk, concave above, flat below, cut square in front and at the anterior parts of the sides, notched laterally and narrowed behind the cotyloid fossm, and terminated backwards in a concave arch.