228 THE ANATOMY OF VEETEBRATED ANIMALS. 



as in most existing Lacertilia (2, 3, 4, 5, 3). In the pes, again, 

 the number of the phalanges is characteristically Lacertilian 

 (2, 3, 4, 5, 4), and so is the form of the fifth metatarsal; bixt the 

 two proximal tarsal bones appear to have been less closely 

 connected together than in existing Lacertilia, and there 

 were, at fewest, three distal tarsal bones with which the 

 metatarsals articulated, and by which they were completely 

 separated from the proximal tarsals. Among existing 

 Lacertilia an arrangement similar to this is met with only 

 in the Ascalabota. 



5—9. The great majority of existing Lacertilia belong to 

 the proccelous Kionocrania, with not more than nine cervical 

 vertebras, and they deviate but little in their osteology from 

 the general type of organization which has been described. 



The gkuU in the Platynota, or Monitors of the Old World, 

 with the American genus Heloderma, differs from that of 

 any other Lacertilia in the circumstance that the nasal 

 bones are represented by a single narrow ossification. 



In the genus Lacerta the bones of the roof of the skull 

 become continued into dermal ossifications, which roof 

 over the supra-temporal foss^. In the Chalcidea and Scin- 

 coidea, in which the body sometimes becomes elongated and 

 snakelike, and the limbs rudimentary, the supra- and infra- 

 temporal arcades are apt to be ligamentous, and the post- 

 frontals and squamosals small. 



10. The DoJichosauria. — A very singular Lacertilian found 

 in the Chalk, and resembling an eel in form and size, has been 

 described by Professor Owen under the name of Dolicho- 

 saurits. It possesses an exceedingly elongated body, but is 

 provided with limbs and with a distinct sacrum, consisting of 

 two vertebrse. Its most remarkable peculiarity, however, 

 lies in the number of its cei-vical vertebrae, which were not 

 fewer than seventeen. 



11. The Mosasanria. — The cretaceous rocks of Europe 

 and America have yielded another remarkable long-bodied 



