practically without function, parallel cases being found among various Scincidae and other Lizards. The HYOID APPARATUS is still very primitive in many, especially in larval, Urodela. Besides the hyoid there are as many as four pairs of branchial arches, which, however, decrease in size and completeness, so that the last two have lost their connection with the median copular piece, and become attached in various ways to the second branchial arch. This is the arrangement apparently in all larvae, but four pairs of branchials persist in the adult _Siren_, _Amphiuma_, and _Cryptobranchus alleghaniensis_. The whole branchial apparatus is reduced to three pairs of arches in _Necturus_ and _Proteus_, to two in the adult _Cryptobranchus japonicus_ and in the Salamandridae. Of considerable interest is the vestige of a fifth pair of arches in the larvae of _Triton_ and _Salamandra_, in the shape of a pair of tiny cartilages, which lie in front and on each side of the opening of the trachea, and give rise to the formation of the laryngeal cartilages, better developed in the higher Vertebrata. The following are noteworthy characters of the SKULL OF URODELA. The articulation of the skull with the vertebral column is not always effected entirely by the two condyles of the lateral occipital bones, but the median basal cartilage often possesses a pair of facets for the odontoid-like process of the first vertebra; such additional facets are perhaps best developed in _Cryptobranchus_ and in the Salamandrinae. The middle portion of the primitive cranium, from the exit of the optic nerve to the ethmoid cartilage, is formed by a pair of separate bones, the orbito-sphenoids. The parietal and frontal bones remain separate. One or more periotic bones exist, besides the prootic, in the aquatic families. {17}A pair of prefrontal bones is present in most Salamandridae, e.g. _Salamandra_, _Triton_, _Amblystoma_, especially in the larva, and in _Cryptobranchus_; these bones are absent in _Amphiuma_, _Necturus_, _Proteus_, and _Siren_. [Illustration: FIG. 3.–Skulls of various Urodela. 1, _Salamandra maculosa_, ventral view, and 2, dorsal view; 3, Axolotl stage of _Amblystoma_; 4, adult stage of _Amblystoma_; 5, _Salamandrina perspicillata_ (after Wiedersheim); 6, _Salamandra maculosa_, dorsal view of the lower jaw. _A_, Articulare; _C_{1}_, _C_{2}_, outer and inner occipital condyles; _Ch_, choana or posterior nasal opening; _d_, dentary; _E_, ethmoid; _F_, frontal; _LO_, lateral occipital; _M_, maxillary; _N_, nasal; _No_, nostril; _OS_, orbito-sphenoid; _P_, parietal; _Pf_, prefrontal; _Pl_, palatine; _Pm_, premaxillary; _Po_, prootic; _PS_, parasphenoid; _Pt_, pterygoid; _Q_, quadrate; _S_, angulo-splenial; _Sq_, squamosal; _St_, stapes; _Vo_, vomer; II, VII, X, exits of the optic, facial, and glosso-vagus nerves.]