SIWALIK CROCODILIA, LACERTILIA, AND OPHIDIA. 
23—231 
are not elevated ; in the form of this aperture and the depressed contour of the 
cranial rostrum the specimen is decidedly nearer to the last-named species than to 
Tomistoma schlegeli. 
When viewed from the ventral aspect (fig. 1) the specimen presents a remarkable 
difference both from Q. gangeticus and T. scJielegeli — namely, that the mandibular is 
very much narrower than the cranial part of the rostrum, and that consequently the 
whole of the lateral series of upper teeth are visible from the ventral aspect when 
the mouth is closed, and bite entirely on the outer side of the teeth of the mandibular 
series, instead of interlocking with them. The fourth mandibular tooth^ has an 
elevated alveolus which, as in Tomistoma, is larger than the alveoli on either side ; 
and in consequence of the narrowness of the mandible, this tooth bites entirely on 
the inner side of the considerably smaller fourth upper tooth,^ its summit being 
evidently received into a pit on the inner side of the latter. With the excep- 
tion of the first mandibular tooth being received into a notch instead of a pit, this 
arrangement of the dentition is essentially alligatoroid ; although in the alligators 
the pit for the fourth mandibular tooth is situated behind, instead of on the inner 
side, of the fourth upper tooth ; and the mandibular teeth behind the fourth are not 
placed so much on the inner side of those of the upper series.® The hinder maxillary 
teeth when fully protruded are nearly equal in size to the premaxillary, and their 
alveoli are separated by exceedingly thin partitions : as in Tomistoma, the third upper 
tooth is considerably larger than the fourth. The premaxillse on the facial surface 
of the rostrum extend as far back as the ninth tooth, whereas in Gharialis gangeticus 
they usually r'each the tenth tooth. On the inferior aspect of the mandible the 
anterior extremity of the splenials reaches as far as the ninth lower tooth, and is 
thus slightly in advance of the posterior extremity of the premaxillse on the facial 
aspect of the cranial rostrum ; while in G, gangeticus the splenials do not extend in 
advance of the twelfth or thirteenth mandibular tooth, and there is a long interval 
between their anterior termination on the inferior aspect of the mandible and that of 
the posterior termination of the premaxillse on the facial aspect of the cranial rostrum : 
this probably indicates that the rostrum of the present form was relatively shorter 
than that of G. gangeticus. In Tomistoma schlegeli the premaxillse on the facial aspect 
of the rostrum extend back to the ninth upper tooth, while the splenials extend on 
the inferior aspect of the mandible to the ninth lower tooth, and are therefore 
slightly in advance of the anterior extremity of the premaxillse. In these respects, 
therefore, the fossil agrees with the living species of Tomistoma and differs from 
Gharialis. The dentary portion of the mandible is not expanded at its termination, 
but the general contour of this part is more like that of G. gangeticus than of T. 
schlegeli ; the abrupt upward curvature of the latter being wanting. As already 
1 This tooth has fallen from its alveolus on the right side, hut the large elevated rim of the latter is plainly seen. 
2 As is the case in G gangeticus, the present form has a small accessory tooth between the proper first and second ; so that 
there are really five premaxillary teeth. The same feature occurs in the fossil species of Tomistoma from Malta and Austria, 
{vide supra, pp. 211-212). 
3 Vide Gray “ Catalogue of Shield Keptiles,” pt. 2. p. 24. 
