42 FOSSIL REPTILIA OF THE LONDON CLAY. 



decidedly resembles the Alligator : I allude to the depth of the excavation between 

 the articular cavity (29) and the end of the angular bone (30), and to the lower or 

 higherlevel of the angle itself : the fossil jaw (fig. 5) resembles the Alligator (fig. 6) 

 in this respect more than the Crocodile (fig. 4). 



The alveoli are twenty in number in each ramus of the Crocodilus Uastingsia : the 

 third and fourth are large, of equal size, and close together ; behind these the eleventh, 

 twelfth, and thirteenth are the largest, and the alveolar ridge is raised to support them ; 

 after the seventeenth the summits of the crowns of the teeth become obtuse, and the 

 crowns mammilloid, and divided by a constriction or neck from the fang ; they each, 

 however, have a separate socket, as in the Crocodiles, the septa not being incomplete 

 at the hinder termination of the dental series, as in the Alligator niger figured in my 

 ' Odontography.'* 



Fig. 3, T. II, gives a representation, of the natural size, of the cranial platform 

 of a young Crocodilus Hastingsia in the collection of Searles Wood, Esq. ; the hemi- 

 spheric depressions in the surface of the bone are more regular, distinct, and relatively 

 larger, and the interorbital part of the frontal is narrower, concomitantly with the 

 larger proportional eyeballs and orbits of the young animal. The relatively larger 

 supratemporal apertures form another character of nonage ; but there is no ground for 

 deducing a specific distinction from any of the differences observable between this 

 part of the young crocodile's cranium and the corresponding part of that of the more 

 mature specimen (T. VI). 



Alligator Hantoniensis, Wood. Tab. VIII, fig. 2. 



London Journal of Palaeontology and Geology. 



On reviewing the characters of the skull of the Crocodilus Hastingsicc we perceive 

 that they combine to a certain extent those which have been attributed to the genus 

 Crocodilus and the genus Alligator ; in general form it resembles most the latter, but 

 agrees with the former in some of the particulars that have been regarded by Cuvier 

 and other palaeontologists as characteristic of the true Crocodiles. I allude more 

 particularly to the exposed position of the inferior canines when the mouth is shut. 

 Respecting which, however, I am disposed to ask, whether this be truly a distinctive 

 character of importance ? One sees that it needs but a slight extension of ossification from 

 the outer border of the groove to convert it into a pit ; yet the character has never been 

 found to fail as discriminative of the several species of existing Crocodiles and Alligators 

 hitherto determined. It constitutes, however, the only difference between the skulls of 

 the Crocodilus Hastingsice in the collection of the Marchioness of Hastings and that fine 

 portion of skull now, by the kindness of Mr. Searles Wood, before me, on which he 

 has founded the species named at the head of the present section. So closely, in fact, 



* Tom. ii, pi. lxxv, fig. 3. 



