OSSEOUS SYSTEM. 139 



forming the terminal portion of the vertebral column, and extending 

 nearly to the pubic symphysis, is to be regarded as a caudal 

 vertebra. 



In the Icthyic Reptiles, as also in the Batrachia, with the ex- 

 ception of Pipa, the first cervical vertebra or atlas is distinguished 

 by the absence of transverse processes. It never supports any 

 costal appendages in the true Frogs, though these are present in 

 the Icthyic and Tailed Batrachia under the form of small, pointed) 

 bony processes. The Pipa, among the Anoura, has only upon two 

 of its vertebrae a pair of cartilagino-membranous appendages. In 

 Proteus, Amphiuma, and Siren, only from 7 to 8 vertebrae of the 

 trunk, while in Salamander and Triton, nearly all of them support 

 ribs. The Sternum is very rudimentary in the Sirens and Tailed 

 Batrachia, being here reduced to some cartilaginous lines and 

 laminae. The Toads exhibit the first traces of a distinct sternum, 

 which, as a short bony piece, projects in them posteriorly into a car- 

 tilaginous plate, and abuts against the posterior clavicle. In Pipa, 

 this cartilaginous plate is very broad. Besides the posterior, the 

 Frogs have an anterior osseous piece which rests in front upon 

 the anterior clavicular bone. The Serpentoid genus, Coecilia, which 

 from its having a scaleless integument, and gills at an early period 

 of its existence, has been referred by systernatists to the Batrachia. 

 presents a perfect anomaly in the fact that all the vertebrae, with the 

 exception of the atlas and some few caudal vertebrae, bear short ribs. 

 The number of its vertebrae is also very great, amounting in Coecilia 

 lumbricoidea to upward of 200. 



The vertebrae of the Ophidia are short and strong, the bodies 

 concave anteriorly, and provided behind with a spherical head, arti- 

 culating in a ball and socket fashion with the vertebra next suc- 

 ceeding. The vertebrae are united moreover by means of the 

 anterior and posterior oblique processes, which present eight 

 articulating surfaces invested by cartilage, arid surrounded by 

 capsular ligaments, sufficiently loose to admit of a great degree of 

 mobility, but at the same time of an adequately firm union between 

 the several bones. Superior spinous processes, short and broad, 

 are generally met with, and frequently also, inferior spinous pro- 

 cesses. The first vertebra, or usually the first two vertebrae, belong to 

 the neck, being destitute of ribs. The succeeding vertebrae, support 

 large, strong, cylindrical and arched ribs, with short appended costal 

 cartilages ; they are very moveably attached by concave articulating 

 heads to the corresponding, smooth, rounded transverse processes of 



