Cope.] 256 [January 20, 



vertebrae, forming a much longer series, and embracing a more ophi- 

 dian visceral cavity, than b seen in the other reptilian types. An 

 important section of the order possesses the zygosphen articulation 

 and vertebrae closely resembling those of the serpents. The dia- 

 pophyses present the vertical costal articular face of the Boas. The 

 immensely long tail, used as a powerful swimming organ, is flattened 

 as in the sea snakes, while its chevron bones are a lacertiUan rather 

 than ophidian character. 



The probtic extends from the basioccipital to the parietal, and 

 overlaps the latter by its superior anterior margin ; this does not oc- 

 cur among LacertiUa, except in aberrant forms, but is common to aU 

 serpents. There is a strong superior and anterior ala on the sphe- 

 noid, which articulates with an alisphenoid. 



The ribs are cylindrical throughout much of their length, and re- 

 semble those of serpents and lizards in theu* articulation, by a com- 

 pressed vertical head, to a vertically compressed dia23ophysis. 



With respect to the characters in which this order is identical with 

 the Lacertilia, the following observations may be made. 



The brain case appears to be unossified anteriorly, as in tortoises, 

 crocodiles and lacertilians, and the parietal both descends, as in 

 Testudinata, and the alispenoid ascends, as in Crocodilia. 



The scapulae and coracoids are not very different from those of 

 lacertilians, and are not coalescent. The scapula appears to have 

 had an angle or process similar to the jirocoracoid, wliile the coracoid 

 is entirely without the emarginations common to Lacertilia. No trace 

 of claviculus, mesosternum or xiphisternum has been found. On the 

 whole, the scapular arch is quite as likely to be similar to that of the 

 Sauropterygia, at that of the Lacertilia. 



The attachment of the palatines to the maxillaries is a lacertilian 

 feature. 



The OS quadratum is like that of the Lacei'tilia in its form and its 

 support by two suspensoria. It is as mobile as in the serpents, and 

 differs from that of both these orders in enclosing the meatus audito- 

 rius behind by a large decurved process. In this these animals re- 

 semble the Testudinata, but in this only, for it is not attached to the 

 prootie in front as in them. 



In both families of the order there is a zygomatic or squamosal 

 arch, but it is very doubtful whether any malar arch exists. There is 

 no connection by malar or quadrato-jugal posteriorly. 



The chevron bones of the caudals, as is well known, are highly 



