642 BRITISH FOSSIL REPTILES. 



corresponded in size with the subject of fig. 2, bui offered no character by which 

 it could be legitimately removed from the genus Goniopkolis. I commence with the 

 description of this small but well-marked species. 



Genus — Goniopholis, Owen} 

 Species — Goniopholis tenuidens, Ow. Crocodilia, Plate 42, fig. 1. 



The dental character of the Amphicoelian genus Goniopliolls consists of the numerous 

 close-set, fine, longitudinal ridges of the enamel, two of which, larger and sharper tlian 

 the rest, traverse opposite sides of the tooth from the base to the apex of the crown, 

 midway between the convex and concave lines of the curvature of the tooth, that is, at 

 the fore and back parts of the crown.^ 



The general shape and proportions of the tooth-crowns indicate distinctions of species 

 of Goniopholis. The type of the genus is characterised by the thickness and subcircular 

 section of the crown, and the obtuseness of that in the posterior teeth. 



In Goniojjholis simus^ the proportion of breadth to length of crown is less than in 

 G. crassidens, and this difference is more marked in the specimen from the Feather- 

 bed of Purbeck which forms the subject of fig. 1, PI. 42. 



This specimen consists of the chief part of the dentary and co-articulated splenial 

 elements of both rami of the same mandible, partially dislocated at the symphysis. The 

 alveolar tract includes the incisive (?) and molary {■>») convexities, without an intervening 

 laniary rising. The incisive convexity includes five sockets, a tooth being retained in the 

 first, third, and fourth on the right, and in the first and third sockets on the left dentary. 

 The foremost tooth has a crown of 6 mm. length and barely 2 mm. of basal breath ; each 

 has partially emerged from a socket larger than itself, and exhibits a portion of a tooth 

 in succession to one which has been lost or shed. The socket is separated by an interval of 

 2 mm. from the second. This shows a subcircular aperture of 5 mm. in diameter. The 

 third socket opens at 2 mm. distance from the second. The tooth [h) in the right dentary 

 shows the inner, longitudinally concave side of the crown, with a basal breadth of G mm. 

 and a total length of 16 mm. One may count about a dozen fine longitudinal linetir 

 ridges between the fore and hind stronger ones (ib., fig. 1 b and b', magn.). The corre- 

 sponding tooth (ib.jfig. 1 a, magn.)in the left dentaryshows the outer longitudinally convex 

 side of the crown, with about sixteen fine ridges. These teeth answer to, or interlock 

 with, the premaxillary or anterior canines of the upper jaw. The fourth tooth (ib. c) is less 

 than the third; its crown projects 10 mm. from the right dentary; the fractured base of 



1 'Reports of the British Association,' 8vo., 18-11, "On British Fossil Reptiles," part ii, IS4I, 

 p. C90. 



2 Loc. cit., pp. 69, 70. 

 2 Ib. ib., p. 7, pi. V. 



