202 AUSTRALIAN CROCODILES 



from which the avian originated. The most obvious dis- 

 tinctions between recent reptiles and birds are of course 

 the presence in the latter of an epidermal covering consisting 

 of feathers, the transformation of the fore limbs into wings, the 

 reduction of the tail from the normaMy long reptilian type to a 

 short coccyx, and the complete absence of teeth ; but the 

 importance of these seemingly insurmountable differences is 

 greatly minimised by the discovery within recent years of fossil 

 forms absolutely intermediate between the two classes, such as 

 the ArdKi.optenjx, a fossil feathered organism from the litho- 

 graphic beds of Solenhofen, Bavaria, belonging to the oolitic 

 period, whose avian affinities are now universally recognised, 

 notwithstanding the presence of a long reptilian tail ; and of 

 the adontornithean fossils from the Mesozoic beds of the Rocky 

 Mountains, which are extinct birds, furnished with functional 

 teeth in both jaws. With data such as these before us, it is 

 impossible to deny that birds are the descendants of some 

 branch or branches of the reptilian type, in which the power of 

 flight was developed, and along with it other anatomical 

 characters by which birds are distinguished from existing 

 reptiles. 



Four orders of reptiles are represented in the present 

 geological epoch, one of which, the Rlujnchocephaliit , still 

 lingers on in the single species Sphenodon punctatns, the limit 

 of whose range is restricted to the islands in the Bay of Plenty, 

 North Island, New Zealand, where it is known to the Maoris as 

 the " TiKdcra,"' and lives in holes in the ground, either 

 excavated by itself, or for nesting purposes by the Mutt-on 

 Birds, upon the young of which, with other small animals, it 

 subsists. The three remaining recent orders are the Emydomuria 

 (Gharials, Crocodiles, Alligators, &c.), the Ghelonia (Tortoises, 

 Turtles, Terrapins, ifcc), and the Sijuamatu, which is divisible 

 into two readily distinguishable suborders, the Lacertilia 

 (Lizards) and the Ophvlia (Snakes). 



With regard to the geological distribution of reptiles, the 

 earliest remain« at present known belong to the Upper 

 Carboniferous deposits of Nova Scotia, and consist of a pair of 

 deeply . amphicoelous vertebrte, believed to be those of a 

 labyrinthodont animal, to which the name F.osaunis acadicus 

 has been applied. During the Permian era reptiles belonging 

 to the rhynchocephalian type appear, in all of which the 

 vertebrae still continue amphicoelous. Coming to Mesozoic 



