1869.] 255 [Cope. 



thotic. It appears also to be homologoiis to, and analogous with, the 

 suspensoriu'm of the Ophidia; hence I conclude that the latter bone 

 is the opisthotic and not the squamosal, as given by Huxley (Elements 

 Compar. Anatomy) ; and the more, as it coexists with a true squamo- 

 sal in these extinct reptiles. Internally it forms a very small, or no 

 part of the walls of the cranium; but it is a solid plug between the 

 embracing laminae of the procitic and exoccipital. The two latter 

 bones are therefore unusually and peculiarly prolonged outwards, 

 and unite by their edges on both the upper and inferior faces of the 

 suspensorium. The fenestra ovalis is at the base of the infero-poste- 

 rior face of the latter, and entei-s an exceedingly small vestibule. The 

 fenestra rotunda is immediately below it, and is funnel-shajDed, with a 

 small orifice. In the small development of the auditory apparatus, it 

 is again like the serpents. 



The mandibular arch is very much like that of serpents. The lack 

 of symphysis gave each ramus the independent motion which they 

 possess in the Ophidia. The articulation of the splenial is a char- 

 acter not seen in any lacertiliau, but is highly characteristic of the 

 boaeform serpents of the genera Loxocemus and Eryx, though it 

 does not occur in Boa proper, nor in many other serpents. This has 

 allowed of considerable motion, as the bones of the ramus above it 

 are scarcely united by a squamosal suture, and the dentary terminates 

 abruptly in a furcation of the coronoid, etc. This termination, 

 with the articular faces of the inferior elements, is characteristic of 

 fragments not uncommon in the cretaceous beds, and which have 

 never In this country been referred to their place. The coronoid 

 bone also Is developed only as In the few serpents that possess it, — as 

 Eryx, Xenopeltis and Boa; Goldfuss notices its great anterior pro- 

 longation and curvature, and overlapping of the extremity of the 

 dentary. Finally the obtuseness and abbreviation of the angle of 

 the jaw is ophidian, rarely lacertilian. The distinctness of the angu- 

 lar bone is, on the other hand, a lacertilian feature. 



In the genus Clldastes, the pterygoid bones are distinct, except at 

 their anterior extremity, as In serpents, and bear a lono- series 

 (17 e. g.) of teeth, i-esembllng thus the serpents. 



The vertebral column closely resembles in many features that of 

 the serpents. It is longer, and contains more numerous vertebra; than 

 any lacertilian or saurian type, and has, therefore, a much more 

 slender form than they. The ribs are cylindric, as in serpents, and 

 ai-e present throughout the cervical, long dorsal and lumbar series of 



