14 PROF. HUXLEY ON THE SPECIFIC AND GENERIC 



dilm homhifroiis ; and on examining the two crania thus named in 

 the British Museum collection, one of which is 20 and the other 

 21 inches long, I can discover no distinguishing character be- 

 tween them and those already described. There can be no doubt 

 then, I think, that these constant and well-marked characters, 

 exhibited by fourteen skulls which vary in length from 5i to 

 21 inches, prove the existence of a distinct species of Crocodile, 

 which I would provisionally term homhifrons. 



I believe that this species has been constantly confounded 

 with hiporcatus, from which it may be at once distinguished by 

 the direction of the premaxillo-maxillary suture, and by the shape 

 of the snout behind the canine groove. I have found these dis- 

 tinctions to hold good at all ages ; but the last-mentioned differ- 

 ence is far more marked in middle-aged than in either young or 

 old specimens. 



All the skulls named Crocodilus palustris which I have seen are 

 referable either to G. liporcatus or to C. homhifrons. With respect 

 to the C. palustris of Lesson and Dumeril and Bibron, the latter 

 authors consider it to be only a variety of C vulgaris. Their descrip- 

 tion would, however, apply very well to C. homhifrons, as I have de- 

 fined it above ; and they expressly state (' Erp. Generale,' t, iii. 

 p. 113) that all their specimens (twelve in number and varying in 

 length from 30 centimetres to more than 3 metres) came from the 

 East Indies or the Seychelle Islands. Now, Dumeril and Bibron 

 enumerate only three Asiatic Crocodiles — C. hiporcatus, C. palus- 

 tris, and C. galeatus, the last of which was only known to them 

 by description ; so that aU the numerous Asiatic crocodiles which 

 passed through their hands belonged either to C. hiporcatus or C. 

 palustris. On the other hand, all the skulls of crocodiles from Asia 

 which I have met with (amounting to at least twenty) are either 

 those of C, hiporcatus or of the species which I have called horn- 

 hifrons\ so that I suspect the latter title will turn out to be a 

 synonym oi palustris. 



6. Crocodilus rhomhifer. 



I have not been able to obtain any skull of this species, which, 

 according to Cuvier's account and figures (' Oss. Eossiles,' t. ix. 

 p. 102), resembles C. Americanus in the great convexity of its 

 nasal region, but differs from it in the greater breadth of the skull, 

 and in the strong converging preorbital ridges, which appear to be 

 limited to the lachrymal bones. If the figures are to be trusted, 

 however, there are other very important distinctive characters 



