3S FOSSIL REPTILIA OF THE LONDON CLAY. 



but is applied to a groove upon the side of the upper jaw, and is exposed. Fig. 1, 

 T. VI, shows that the prefrontal (14) and lachrymal (73) bones, instead of descending 

 much less upon the facial part of the skull, extend much more, and advance nearer to 

 the end of the muzzle than in any Alligator, or even than in any actual species of broad- 

 nosed Crocodile. 



The vacuities left between the postfrontal (12), the parietal (7), and the mastoid (8) 

 (T. VI, fig. 1, and T. II, fig. 3), are as wide as in the skull of a Crocodilus biporcatus 

 of equal size, and are larger than in the Alligator lucius or All. sclerops. Fig. 2, T. VII, 

 shows that no part of the vomer is visible between the premaxillaries (22) and maxillaries 

 (21), or elsewhere on the palate. But the palatine expansion of the vomer is not a 

 constant character ; it is wanting, for example, in the Alligator lucius of North America. 

 The palatines (20) are not more advanced in the fossil in question than they are in the 

 true Crocodiles, and their anterior portion does not expand to its anterior truncated 

 termination. The posterior nostril, the entire contour of which is shown in the portion 

 of the skull of the same species figured in T. VI, fig. 3, is longer than it is broad. 



There is but one character in which the fossil skull in question differs from the 

 true Crocodile, and agrees with most species of Alligator ; it is in the reception of 

 the two anterior teeth of the lower jaw into cavities of the premaxillaries, shown in 

 fig. 2, T. VII, which are not perforated ; so that there are no foramina anterior to the 

 bony nostril, as in T. I, in the bone marked 22. These foramina are not, however, 

 absent in all Alligators ; the skull of the Alligator sclerops, figured by Cuvier (torn, cit., 

 pi. i, fig. 7), shows them, as do all the species of true Crocodile the skulls of which are 

 figured in the same plate. There is one character by which the Crocodilus Hastingsiee 

 differs from all known species of both. Crocodile and Alligator : it is that afforded by 

 the broad and short nasal bones (15, fig. 1, T. VI), which do not reach the external 

 nostril ; this being formed, as in the Gavials, exclusively by the premaxillaries 22. 



In the general proportions, however, of the skull of Croc. Hastingsiee, especially 

 the great breadth, shortness, and flatness of the obtusely-rounded snout, it resembles 

 that of the Alligators more than that of any known species of true Crocodile, the length 

 from the tympanic condyle to the end of the snout being to the breadth taken at the 

 condyles as 16 to 9. 



The following are dimensions of the fossil in question : 



Length of skull from the angle of the lower jaw to the 



end of the snout 



Do. from the tympanic condyle to ditto 



Do. do. to the orbit 



Do. from the orbit to the external nostril 



Breadth of the skull across the tympanic condyles 



Do. the orbits 



Do. the external nostril 



Longest diameter of upper temporal aperture 



Do. the post-palatal vacuities 



Depth of the lower jaw at the posterior vacuity 



Depth of the occipital region 



Feet. Inches. Lines. 



1 



6 



6 



1 



4 



6 







5 



4 







7 











9 



3 







7 











4 











1 



9 







4 



9 







3 











4 



3 



