12 PROr. HUXLEY ON THE SPECIFIC A.KD GENEEIC 



sible that it can be a Mecistops. But, in addition to this, I had 

 the good fortune to find, among the recent additions to that excel- 

 lent osteological collection which Dr. Gray has gradually formed 

 at the British Museum, the skull of a Crocodile obtained from a 

 dealer in Paris, and labelled by him " Croc, de I'Orinoke." I at 

 first imagined this Crocodile to be a Mecistops ; but on careful in- 

 vestigation it turned out to be no other than the skull of a Oroco- 

 dilus Journei, somewhat larger than the Bordeaux specimen, but, 

 as the subjoined measurements will prove, agreeing with it in all 

 its proportions : — 



Inches. 

 Length from end of snout to end of ossa quadrata. . . 22^ 

 Breadth between outer margins of ossa quadrata . . . 9| 



at the level of the anterior margins of the 



orbits 5|- 



at the tenth tooth 3|- 



at the end of the snout 2|- 



of the interorbital space If 



Length of mandibular symphysis . 5 



Now Dumeril and Bibron expressly state that the length of the 

 head of C. Journei equals 2^ times its greatest transverse diameter, 

 that the width of the jaws at the anterior margins of the orbit 

 equals one-fourth the length of the head, and that at the tenth 

 tooth it equals one-sixth the length of the head ; and these are as 

 nearly as possible, it will be observed, the relations of the same 

 dimensions in the above list. 



In the specimen in the British Museum there are eighteen teeth 

 on each side above, and fifteen below. The Bordeaux specimen is 

 stated to have the same dental formula, except that there are six- 

 teen teeth in the left ramus of the mandible. The fourth and tenth 

 maxillary teeth are stated by Graves to be as large again as the 

 others ; and the corresponding alveoli have these proportions to 

 one another in the British Museum specimen. In fact, there can 

 be no doubt that this skull is that of a true Crocodiltts Journei. 



But its general characters at once prove the close affinity of 0. 

 Journei with the other true Crocodiles, from which it differs only 

 in its elongated and gradually tapering skull, and in the more 

 backward extension of the mandibular symphysis*, which attains 

 the level of the posterior margin of the sixth tooth. 



In this character, and in the extreme slenderness of the snout, 



* The greater proportional length of the symphysis is noted by Dumeril and 

 Bibron. 



