PURBECK CROCODILES. 643 



the corresponding tooth in the left dentary is 4 mm. in diameter. Seven close-set 

 sockets follow along the feebly concave part of the alveolar tract. The tooth of the 

 twelfth socket at the beginning of the second convexity is preserved in both rami ; its 

 crown is 8 mm. in length, 4 mm. in basal breadth, with an obtuse summit, showing the 

 feeblest indication of an apical point. This point is rather better seen in the crown of 

 the next tooth, which has not wholly emerged. 



The total number of teeth is sixteen in each of the dentary elements here preserved, 

 and by analogy to the Goniopholis shnus^ the whole, or nearly the whole, of the dental 

 series or sockets, in one dentary element is here exhibited. 



The outer surface of the dentary is pitted by small subcircular, not close-set, 

 impressions, except on the outer alveolar plate of the molary rising, where a few 

 longitudinal pits indent the otherwise smooth surface of the bone. 



The length of the symphysis is 25 mm., the depth 10 mm. The extreme breadth 

 of the incisive part of the mandible is 32 mm. 



The length of the preserved alveolar part of the dentary is 85 mm. (3 inches, 

 3 lines) ; the length of the entire mandible might have been between 5 and G inches. 



Fragmentary evidences of the Goniopholis tenuidens in other slabs of matrix do not 

 indicate any individual of a larger size than is exemplified by the above-described 

 portion of lower jaw. 



The mandible of Goniopholis crassidens, with an extreme depth of 4 inches, attained 

 the length of 2 feet. Of this length the alveolar part of the dentary element occupied, as 

 in most broad-faced Crocodiles, one half. The length of the alveolar part of the 

 mandible of Goniopholis tenuidens being 3 inches, the total length of the jaw may be set 

 down at one fourth of that of the type species of the genus. 



Genus — Brachydectes, Owen} 



Species — Brachydectes major, Ow. Crocodilia, Plate 42, fig. 2. 



In this genus and species a left mandibular ramus, 9 inches 6 lines in length, shows 

 an alveolar tract of but 3 inches 9 lines in length. In the proportion of the jaw, there- 

 fore, appropriated to the lodgment of the teeth this Crocodile differs from the rest of the 

 family. The ramus has a less relative depth than in Brachydectes minor, fig. 3 ; it 

 measures in extreme vertical extent, taken at about one fourth of the length from the 

 angle, 1 inch 9 lines, or little more than one sixth the entire length of the ramus, 

 whilst in Br. minor the extreme depth of the mandible, which is about midway between 

 the two ends, is nearly one fifth of the entire length of the ramus. This proportion 

 might, however, be deemed an immature character of the smaller specimen, but there are 



1 Gr. ^jin-^vs, short ; Sj/kd/s, biter. 



