BY J. DOUGLAS OGILBY. 203 



times we find reptiles in great abundance, and in a high state of 

 development, so much so that this has been called the " Age of 

 Reptiles." Among the Triassic forms worthy of notice may be 

 mentioned the predecessors of the existing crocodilians, but 

 difiering from them in having amphicoelous vertebrsE and 

 anterior choan<T, as also in lacking the dilatation of the palatine 

 and pterygoid bones so characteristic of the present species. 

 These Triassic forms increase in number and variety, and 

 become more enormously developed in size during the Jurassic 

 period, which is also remarkable in possessing the earliest 

 chelonian remains, and these not materially differing from the 

 existing families. It is, however, to the Cretaceous period that 

 we must look for the greatest variety of reptilian life and the 

 culminating point in its development ; during thi^ era there 

 appeared gigantic marine monsters, having a snake-like body 

 and very short limbs, and attaining a length of at least eighty 

 feet. Here also the first extinct crocodiles having procoelous 

 vertebifB and posterior choanfe occur. Marine chelonians, 

 allied to the Leathery Turtle {Dennatochelys coriacen), also make 

 their appearance. Towards the close of this period, however, 

 its abundant reptilian life was almost totally annihilated. 

 "With the exception of a few genera allied to the dinosaurians 

 the Tertiary reptiles belong to the present faunic type ; here the 

 more ancient forms of the Emydosauria are entirely superseded 

 by true crocodiles, gharials, and alligators, and the earliest 

 ophidian remains occur in the Pleistocene deposits of France, 

 and more especially of India; while during the Eocene period 

 several innocuous genera, mostly of large size, appear. 

 Chelonian remains are numerous throughout all the Tertiary 

 formations, and approximate so closely to recent types as to be 

 in many cases specifically indistinguishable. 



The geographical distribution of reptiles is a subject too 

 large and complex to receive more than a passing mention here ; 

 it is sufficient, therefore, to point out that being cold-blooded, 

 air-breathing animals, their natural home is to be looked for in 

 the tropical and subtropical zones, and accordingly we find that 

 it is within those limits that they have attained their highest 

 development whether as regards size, variety of form, or beauty 

 of coloration, while beyond these limits reptiles rapidly decrease 

 in numbers, and entirely disappear within the polar circle. 



The Emi/dosauria, to which subclass the subjects of this 

 article belong, may be briefly described as having a lacertiform 



