1 148 CLASS REPTILIA. 



tebrse (fig. 1051) differ from those of the Pythonidce, (fig. 1050) by 

 their much taller neural spines, the lower position of the costal 

 articular surfaces, the less divergence of the zygapophyses, and by 

 the stronger development of the haemal ridge on the inferior aspect 

 of the centrum, which often carries well-marked processes at its 

 two extremities. The type genus Palceophis is represented by three 

 English species, of which the largest is estimated to have attained 

 a length of 20 feet. In the Eocene of North America we have 

 closely allied forms reaching to a length of 30 feet, which are re- 

 ferred by Professor Marsh to a distinct genus under the name of 

 Titanophis (Dinophis), but which Professor Cope regards as indis- 

 tinguishable from Palceophis. By Sir R. Owen these snakes are 

 regarded as allied to the existing marine Sea-snakes or Hydrophidce. 



Family Elapid^e. — The first existing family of the section 

 Colubriformes Venenosi includes the Cobras (JVaia, fig. 105 1, bis) 

 and Coral-snakes (Elaps). The former genus probably occurs in 

 the Pleistocene of Madras ; and perhaps also in the Middle Miocene 

 of Steinheim, in Bavaria. 



Family Viperid^e. — The present and following families consti- 

 tute the section Viperiformes ; characterised, among otherTeatures, 

 by the perfect development of the poison-apparatus. A snake from 

 the Upper Miocene of Switzerland has been referred by M. Roche- 

 brune to the existing genus Bitis {Echidna) ; having been originally 

 described under the name of Coluber Kargi. 



Family Crotalid^e. — The Pit- Vipers and Rattlesnakes are con- 

 fined at the present day to Asia and America. The genus Neuro- 

 dromicius, from the Miocene of North America, is provisionally 

 referred by Professor Cope to this family; while Laophis, from 

 the Tertiary of Salonica, has also been regarded as a member of 

 the same group. 



Ordinal Position Uncertain. — It will be convenient to men- 

 tion here two imperfectly known genera from the English Purbeck, 

 of which the ordinal position cannot at present be determined. 

 They were regarded by Sir R. Owen as belonging to the Lacertilia, 

 but their teeth are much more of a Dinosaurian type. The first 

 genus, Nythetes (JYuthetes), is represented by a species of the size of 

 some of the existing Varanidce, but has teeth closely resembling those 

 of the Megalosauridce, although it is said that they were not implanted 

 in distinct sockets, and were anchylosed to the bone. The second 

 genus, Echinodon, is a smaller form, in which the teeth present a 

 striking resemblance to the much larger ones of the Dinosaurian 

 genus Scelidosaurus ; they were implanted in imperfect sockets. 



Here also may be mentioned the remarkable genus Atoposatirus, 

 from the Kimeridgian lithographic limestones of Bavaria, which 

 includes two species of small Lizard-like Reptiles, presenting the 



