238 FOSSIL REPTILES. 



from the orbit, is much longer and narrower. The parietal sur- 

 face between the two crotaphidians is more elongated. The 

 occipital crest is not in a right angle, but in a very slender, 

 trenchant lamina, extending from the parietal to the mastoidean 

 angle. On the occipital face the mastoidean angle is not unin- 

 terruptedly united with the back of the articular apophysis of 

 the OS tympani. It is separated by a deep depression, above 

 which advances a trenchant crest, which belongs to the lateral 

 occipital. The mastoidean bone has a concavity in its descend- 

 ing part, of which there is no trace in the gavial. The emargi- 

 nation of the lower edge of this face between the articular 

 apophysis of the os tympani and the tuberosity of the basilary 

 bone, is much less than in the gavial ; and, consequently, this 

 apophysis is less salient towards the bottom, and less detached. 



On the lower face of this head the palatines do not close the 

 nasal cavity underneath, but opposite the posterior edge of the 

 great palatine foramen. So that the hinder nasal fossa is very 

 large, and does not open but towards the extremity of the 

 basilary face, where, in the common crocodiles, the back nos- 

 trils are situated a little before the foramen of the arteries 

 The pterygoidean wing is not widened externally, as in all the 

 crocodiles, but is contracted by a broad emargination in the 

 part where it is about to unite to the bone. 



On the lateral face of this head, the orbital edge of the jugal 

 is not raised, and does not leave behind it a deep emargination, 

 as in the gavial. The jugal does not re-ascend to articulate 

 with the posterior frontal, but, on the contrary, this last de- 

 scends to unite itself with the jugal, at the external edge of 

 the orbit, at its posterior angle. The vacancy between the 

 orbit and the anterior edge of the os tympani is greatly elongated 

 in the fossil, and occupies four-fifths of the temporal fossa ; so 

 that the tympanic cavity is much shorter and more thrown 

 behind. The anterior part of this temporal /oss is also very 

 narrow and acute, which gives it quite another figure from that 

 of the gavial. The bone which is analogous to the stapes, and 



