The frontals and parietals on each side are united so as to form a pair of fronto-parietals, and a girdle-like sphenethmoid is present. The quadrate is not generally ossified. A predentary or mento-meckelian bone is commonly present in the mandible, and a single bone represents the angular and splenial. The branchial arches are much reduced in the adult, and the distal ends of the cornua unite to form a flat basilingual plate of a comparatively large size. Ribs are very little developed. Clavicles are present. The ilia are very greatly elongated. The anterior limb has four well-developed digits and a vestigial pollex, and is of moderate length; the radius and ulna have fused. The posterior limb is greatly elongated and is pentedactylate; the tibia and fibula are fused, while the calcaneum and astragalus are greatly elongated, and it is largely owing to them that the length of the limb is so great. The group includes the Frogs and Toads, the predominant Amphibia of the present time. FOOTNOTES: [50] T.H. Huxley, _Amphibia_ (_Encyclopaedia Britannica_). [51] See R. Wiedersheim, _Morphol. Jahrb._ Bd. III. 1877, p. 459. [52] See A. Fritsch, _Fauna der Gaskohle_, Prague, 1883-85-86, also writings of Cope, Credner, Huxley, H. v. Meyer, Miall. [53] See R. Wiedersheim, _Anatomie der Gymnophionen_, Jena, 1879. CHAPTER X. THE SKELETON OF THE NEWT (_Molge cristata_). I. EXOSKELETON. The skin of the Newt is quite devoid of any exoskeletal structures. The only exoskeletal structures that the animal possesses are the teeth, and these are most conveniently described with the endoskeleton. II. ENDOSKELETON. The endoskeleton of the Newt, though ossified to a considerable extent, is more cartilaginous than is that of the frog. It is divisible into an =axial portion= including the vertebral column, skull, ribs, and sternum, and an =appendicular portion= including the skeleton of the limbs and their girdles. 1. THE AXIAL SKELETON. A. THE VERTEBRAL COLUMN. This consists of about fifty vertebrae arranged in a regular continuous series. The first vertebra differs a good deal from any of the others; the seventeenth or sacral vertebra and the eighteenth or first caudal also present peculiarities of their own. The remaining vertebrae are divided by the sacrum into an anterior series of =trunk= vertebrae which bear fairly large ribs, and a posterior series of =caudal= vertebrae, all of which except the first few are ribless. THE TRUNK VERTEBRAE. Any vertebra from the second to the sixteenth may be taken as a type of the trunk vertebrae.