io6o 



CLASS REPTILIA. 



with the exception of having no horizontal processes. The height 

 of the spine in one species is more than twenty times the length 

 of the centrum ; and Professor Cope concludes that these spines 

 formed a kind of elevated fin on the back, of which it is difficult 

 to imagine the use. Naosaurus differs from the preceding by the 

 above-mentioned horizontal processes on 

 the spines of the vertebrae (fig. 981). 

 The premaxilla had one tusk • and there 

 were two similarly enlarged teeth near the 

 anterior extremity of the maxilla, behind 

 which comes a series of some twelve teeth 

 of equal size, with compressed and slightly 

 recurved crowns. Numerous small obtuse 

 teeth are also dotted over the palatines and 

 pterygoids. This genus has also been re- 

 corded from the Permian of Bohemia. 

 Other American genera included in this 

 family by its founder are Embolophorus, 

 Edaphosaurus, Archoeobelns, Theropleura, 

 and perhaps Lysorophus — Theropleura 

 being characterised by the presence of 

 well-developed abdominal ribs. 



Here may be mentioned the genus Ster- 

 eorhachis, from the Lower Permian of 

 France, of which the lateral cheek-denti- 

 tion presents a considerable resemblance 

 to that of Naosaurus, although it is not 

 known whether teeth were present on the 

 palate. The neural spines of the vertebrae 

 are of normal type ; but it is not known 

 whether intercentra were present, or whether 

 the centra were notochordal. The humerus 

 (fig. 982) differs from that of the Galesau- 

 ridcB in the contour of the distal extremity. 

 Professor Seeley regards the above-mentioned humerus from the 

 Karoo system of the Cape, described by him under the name of 

 Propappus, as indicating an allied form, but there is nothing to 

 justify this association. Stereorhachis may constitute the type of a 

 distinct family, but there is at present no evidence to support the 

 view that this genus (together with Propappus) represents a distinct 

 order, for which the name Gennetotheria has been proposed. 



Family Bolosauridje. — This family is also typically known 

 from the reputed Permian of North America, where it is repre- 

 sented by the genera Bolosaurus and Chilonyx. In the former, 

 the teeth are fixed in shallow alveoli, and have their crowns ex- 



Fig. 981. — Anterior view of 

 dorsal vertebra of Naosaurus 

 claviger; from the Permian of 

 Texas. One-sixth natural size. 

 Ce, Centrum. (After Cope.) 



