178 



THE EXTINCT BATRACHIA, REPTILIA 



to, and analogous with, the suspensorium of the Ophidia ; hence I conclude that the lat- 

 ter bone is the opisthotic, and not squamosal, as given by Huxley (Elements Compar. 

 Anatomy); and the more, as it co-exists with a true squamosal in these extinct reptiles. 

 Internally it forms a very small or no part of the wall of the cranium, but is a solid plug 

 between the embracing laminae of the prootic and e.\ occipital. The two latter bones are 

 therefore unusually and peculiarly prolonged outwards, and unite by thin edges on both 

 the upper and inferior faces of the suspensorium. The fenestra ovale is at the base of the 

 infero-posterior face of tin; latter, and enters an exceedingly small vestibule. The fenes- 

 tra, rotunda is immediately below it, and is funnel-shaped, 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 and subarticular is a character not seen in any lacertian, but is highly char- 

 acteristic 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 some motion 

 as tin; bones of the ramus above it are merely united by a squamosal suture, and. the (Uni- 

 tary terminates abruptly between a, sheath of the coronoid, etc. This termination, with 

 the articular faces oi* the inferior elements, are 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 lew serpents that possess it, as 

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

 ture, and overlapping of the extremity of the dentary. Finally the obtusoness and abbre- 

 viation of the angle of the jaw is Ophidian — rarely lacertian. The distinctness of the an- 

 gular hone is on the other hand a lacertian feature. 



The postero-lateral margin of the parietal is decurved and is connected to the sphe- 

 noid by a lateral plate of bone, which is united suturally to tin; latter. \ have been una- 

 ble to find in Clidastes any suture indicating that this piece is an alisphenoid, rather than 

 tin 1 parietal; it appears to belong to the latter bone. If so, it is a. strong Ophidian char- 

 acter ; if it Ik; alisphenoid, it is Chelonian and Crocodilian; no Lacertilian presents a like 

 structure 1 . 



In the genus Clidastes the pterygoid bones are distinct except at their anterior extrem- 

 ity, and bear a long series (17 e.g.,) of teeth, resembling thus tin; serpents. 



The vertebral column resembles in many features that of the serpents. It is longer, 

 and contains more numerous vertebrae than Lacertilian or Saurian types, and has 

 therefore a much more slender form than they. The ribs are cyhndric, as in lizards and 

 serpents, and are present throughout the long dorsal and lumbar series of vertebrae, form- 

 ing a much longer series, and embracing a, more Ophidian visceral cavity than is seen in 



