648 BRITISH FOSSIL REPTILES. 



smooth tract along the anterior border, from 4 to 3 Dim. in breadth. The breadth of the 

 entire scute is 17 mm. ; the length is 35 mm. Some smaller scutes are pentagonal. 



We have here, therefore, evidence of an Amphicoelian Crocodile, with the dermal 

 armour after the type of that of GoiiiophoUs, but generically distinct by the characters of 

 the mandibular dentition. If the dentary bone constituted three fourths the leiigth of 

 the mandible this may be reckoned to have been about 6 inches in length, and the entire 

 Crocodile may have been 6 feet in length. 



The portion of mandible of which the under surface of the dentary and splenial 

 elements are exposed, forming the subject of fig. 6, Plate 43, is shown by certain teeth 

 in place and others scattered near in th& same slab, to belong to the same genus and 

 species as that represented by fig. 1, and to have come from an individual of similar size. 

 Both are the largest evidences of Nannostichm shown in the numerous series of Reptilian 

 fossils from the portions of the ' Feather-bed ' formation now under review. 



The symphysis, 21 mm. in longitudinal extent, forms a fifth part of the preserved 

 extent of the dentary ; the breadth of this part of the jaw is 30 mm. ; that behind the 

 symphysis is 27 mm. The rami, as far as they are preserved, diverge to a breadth of 70 mm. 



The alveolar part of the symphysis describes an incisive convexity, and the sockets 

 indicate one or two teeth of larger size and thicker proportions than those of the rest of 

 the dental series. The crowns of two of these teeth, which had become detached, are 

 fortunately preserved, near the fore part of the jaw. The largest (fig. 7, magn.) represents 

 the ' anterior canine,' and is the homologue of fig. 1 c and fig. 2, magn. It shows the well- 

 marked characteristics of that tooth in Nannosuchits, and, besides the difi'erence of sculptur- 

 ing, the crown is more strongly curved than in Goniopholls or Petrosuchus. The second 

 detached tooth near the incisive alveoli shows both I'oot and crown. The latter is but 

 half the length of that of the ' canine ;' more of the convex side is exposed than in fig. 2 ; 

 it is traversed by fine longitudinal ridges. The teeth which are in place show a smaller 

 size and more slender pointed crown. There is no evidence of any tooth equalhng in 

 size the largest of the symphysial or incisive series. 



The numerous minute circular pits sculpturing the sym])hysial expansion change, as 

 in the specimen (fig. 1), to coarser and larger longitudinal impressions as the rami 

 recede and pass backward ; and the surface near the alveolar border showing the feeble 

 molary convex curve is smooth. 



The dental character of Nannosuchus is more fully exemplified by smaller specimens, 

 of which two, forming parts of the lower jaw, will be first noticed. 



The subject of fig. 8, PL 43, includes the dentary and angular elements, partially 

 dislocated, of the right mandibular ramus. Two of the molary series of teeth are in siltl, 

 showing long, slendei', feebly recurved crowns, each 5 mm. in length ; other teeth of 

 similar shape and with finely striate enamel are on the same slab. 



In a smaller dentary (PI. 43, fig. 9) the sockets of eighteen teeth are visible. The 

 proportions and outer markings agree with those of the larger specimen. 



