OF EECENT CEOCODILIANS. 129 



skull of each of the specimens of the different species in the British Museum Collection ; 

 but I am satisfied that the importance of such tables of measurement is over-estimated : 

 no doubt it has a very imposing appearance ; but a good figure is more useful than any 

 amount of measurement. Every species has its normal measurements ; but these are 

 liable to vary in the different individuals ; and any difference sufficient to show a 

 distinction of species is easily appreciated by the eye, as it must alter the general 

 proportions of the different parts of the head. 



It has been suggested that I ought to give the description of each separate bone of 

 which the skull is composed. This may be of use to the student of comparative anatomy, 

 but is not of so much importance to the zoologist ; for though each bone has a normal 

 form in each species of Crocodile, yet they are each liable to considerable variation 

 within certain limits in the different individuals of the species. 



The bones of the different genera have been described in several works on osteology, 

 and they are well figured by De Blainville and others. 



De Blainville, in his ' Osteographie,' devotes five folio plates to the osteology and 

 dentition of recent Crocodiles, giving details of Crocodilus bijjorcatus, C. lucius, C. 

 vulgaris, C. sclilegelii, C. longirostris, C. rliombifer, and C. sclerops. These plates 

 were prepared to accompany an essay that M. de Blainville was preparing for the 

 ' Memoires de 1' Academic des Sciences de France ' when he died. 



Professor Carl Bernhard Briihl, of the Universities of Cracow and Pesth, has published 

 twenty quarto etchings of the skeletons of Crocodiles and Alligators, giving details of 

 three or four species. The plates are exceedingly accurate, and full of details, being 

 drawn and etched by the Professor and his wife direct from the specimens. They were 

 published at Vienna in 1862. There is a continuation of the work, containmg three 

 additional plates, published in 1865, principally devoted to the canals of the ear-bone. 



I must here refer to a paper by Professor Huxley, entitled " On the Dermal Armour of 

 oiJacare and Caiman, with notes on the Specific and Generic Characters of recent Croco- 

 dilia," Joui-n. Proc. Linn. Soc. Zool. iv. p. 1. As this paper contains an excellent account 

 of the osteological differences between the different genera of Crocodilia, 1 have not 

 considered it desirable to repeat them here, more especially as they were chiefly drawn 

 up from specimens in the British Museum. 



Order EMYDOSAURI (Emydosaurians). 



Emydosauri, Blainville, Gray, Ann. Phil.x. 195, 1825; Cat. Tortoises & Crocodiles Brit. Mus. 38, 1844. 

 Crocodilia, Huxley, Joum. Proc. Linn. Soc. Zool. iv. p. 1. 



The Emydosaurians or Crocodilians may be divided into three families : — 

 A. The cervical and dorsal plates forming one dorsal shield. 

 I. Gavialid^. The large front teeth and the canines in the lower jaw fit into notches 

 in the margin of the upper jaw. 



