202 



EEPTILIA. 



very positively as to tlie exact range of the Laccrtilia in time. 

 This uncertainty arises from two causes — firstly, that there 

 is some doubt as to the exact age of some deposits which 

 have yielded Lacertilian remains ; and secondly, that the 

 affinities of some extinct Eeptiles are a matter of consider- 

 able question. Upon the whole, the oldest known Lacer- 

 tilian would appear to be the Protorosaums (fig. 553) of the 



]\Iiddle Permian roclys, species of which at- 

 tain a length of four feet or more, and have 

 been found at the same geological horizon in 

 botli Europe and Britain. Protorosaurus differs 

 from all existing Lizards in having its teeth 

 implanted in distinct sockets — this being a 

 Crocodilian character. In other respects, the 

 Permian reptile approximates closely to the 

 living JMonitors {Varanidce) , and its slightly- 

 cupped vertebra3 would lead to the belief that 

 it was aquatic in its habits. 



In rocks known, or supposed, to be of 

 Triassic age, numerous Lacertilian reptiles 

 have been discovered, of which the most im- 

 portant are Telerpeton, Hy'pcroda'pcdon, and 

 Rliyncliosmirus. Tdeiydon occurs in strata near Elgin, in 

 Scotland, which have been variously referred to the Upper 



Fig. 553.— Pro^o- 

 rosfMinw Speiieri — 

 Muklle Permian, 

 Tliuringia— reduced 

 in size. (After Von 

 Meyer.) 



