URODELES, Or TAILED AMPHIBLA. • Under this designation the following genera are included :—Pleuro deka, Waite. ; Bradybates, Tech. ; Salam,andra, Linn. ; Pseudosala mandra, Tech. ; Anebystoma, Tech. ; Onychodactylus, Tech. ; Plethodon, Tech. ; Cylindrosoma, Tsch. ; (Edipus, Tech. ; Salantandrina, Fitz. ; Geotriton, Bonap. ; Ilemidactylium, Tsch. ; Cynops, Tech. ; Hynobius, Tack ; Pseudotriton, Tech. ; Triton, Laur. ; Xiphonura, Tech. ; Meg alobatrachus, Tech. (Sieboldia, Bonap.) ; Andrias (fossil) Tech. ; Menoponta, Harl. ; Sired on, Wagl. (Axolotl); Amphiuma, Gard. ; Menobranchus, HarL; Ilypochton, Merr. (Proteus); Siren ; and many others.
Skeleton.—The skull of the Terrestrial Salamander (Lacerta Sala tnandra, tine ; Salam,andra terrestris, Aldr. and Ray) is well described by Cuvicr as being nearly cylindrical, widened in front in order to' form the semicircular face, and behind for the two crucial branches' resembling those of the frogs, and containing the internal ears. But though the composition of the head resembles that of the frogs in the back and under parts, it differs remarkably in other parts : there is no girdling bone Om en ceinture), and the only representation of the ethmoId bone appears in a membranous state.
Above, the cranium is divided nearly equally between the two frontal and the two parietal bones. The anterior part of the frontal bones is articulated forwards with the bones of the nose, and, laterally, with the anterior frontal bones. The apophyses rising from the inter- ' maxillary bones are very large, which places the external osseous nostrils very far apart. The nasal bone is placed on the upper part of each of them, between the intermexillary, the frontal, the anterior frontal, and the maxillary bones. The anterior frontal bone occupies the check in front of the anterior angle of the orbit, but does not descend into the cavity, the anterior wall of which is simply mem branous. Cuvier believed that he saw a very small lachrymal bone at the external angle of the anterior frontal bone. The dental part of
the upper maxillary bone is carried backwards as usual, but without forming a junction with either the pterygold or jugal bones. Cuvier found only two occipital bones, as in the other Batrechians, and each of them was intimately united with a part analogous to the os petrosurn (rocittr). A great round hole serves for the entry to the vestibule, and consequently to the feneetra oralis. In the living animal it is closed by a cartilaginous plate, without any etem, and entirely hidden under the muscles. To this bone, which occupies tho place of both the occi pital, lateral, and petrous bones, are attached three others, the lower of which (the pterygold), with its triangular figure, brings to the mind of the observer the three branches of which it is formed in the frogs. Its anterior angle, as has been stated, does not reach the maxillary bone, and is only connected to it by a ligament ; neither does the internal anglo reach the sphenoid bone : the external angle exists under the second of the three bones here noticed, namely, the inter mediate bone—that to which belongs the facet for the articulation of the jaw. This bone, envier remarks, is very difficult to define ; and he further says that he shall perhaps be considered very rash if he names it the jugal bone, for, far from being placed horizontally, and going forwards to join the maxillary, it lies transversely on the posterior border of the pterygoid bone ; nevertheless, there is a ligament which unites it to the posterior point of tho maxillary bone. The third and upper of these bones lies upon the preceding, and in the Fume direction; it is oblong and fiat, and is attached by its internal extremity upon the lateral occipital bone, without reaching to the parietaL Supposing the jugal bone to be well named, this would be the tympanic bone ; rind, in fact, if the little plate which covers the fenestra ovalis had a handle (months), it would pass behind the bone of which wo speak, as in the frogs it passes behind the tympanic bone.