AUSTRALIAN CROCODILES. 



By J. DOUGLAS OGILBY. 



Read before the Royal Society of Queensland, 30th January, 1904. 



Before proceeding to deal with the subject of this article it 

 will be advantageous to devote a few words to the consideration 

 of the affinities and classification of Reptiles in general as 

 accepted at the present day. 



Popularly speaking, Reptiles are cold-blooded vertebrate 

 animals, breathing throughout existence by means of lungs, 

 having the body protected by scales or scutes, the skull articu- 

 lated with the atlas vertebra by a single convex condyle, and the 

 heart divided into two auricles and an usually incompletely 

 divided ventricle ; the blood of the arterial and venous systems 

 mingles either in the heart or at the origin of the aortic arches ; 

 and the thoracic and abdominal cavities are but rarely separated 

 by a complete diaphragm. All Reptiles are either oviparous 

 or ovoviviparous, the eggs in the former and much more numerous 

 section being enclosed within a shell, which is either hard and 

 calcareous like that of a bird, or soft and pliable. The foetus, 

 like that of mammals and birds, is surrounded by an amnion 

 and an allantois, and is nourished from the yoke of the egg. 



Reptiles are more closely allied to birds than to any other 

 class of vertebrate animals ; with them they agree in the presence 

 of a single basioccipital condyle, the absence of branchiae at any 

 period of postfoetal existence, the articulation of the complex 

 lower jaw to the cranium through the medium of a quadrate 

 bone, and the nucleated blood corpuscles. 



Reasoning from these data the majority of biologists 

 now accept Huxley's theory, that the reptilian type is that 



