270 
SELACHIT. 
Stonesfield mentioned below. In size they are as small as the 
teeth of H. polyprion , but seem to be specifically distinguished by 
the following characters:—Crown of principal teeth high, com¬ 
pressed, with a large erect median cone and two or three lateral 
cones, narrow and acutely pointed; coronal surface of all the teeth 
smooth, except quite at the base, where vertically wrinkled. Root 
depressed, flattened, expanded posteriorly. 
Form. 6f Loo. Bathonian (StonesfieldJSlate): Oxfordshire. 
33474. Type specimen, shown, of twice the natural size, in PI. XI. 
fig. 5 : Ston esfield. Purchased , 1858. 
39203 a. Less perfect tooth ; Stonesfield. 
Boiverbank Coll. 
P. 2182 d. Tooth, posterior aspect, shown, of twice the natural size, 
in PI. XI. fig. 6 ; Stonesfield. The root has a consider¬ 
able rounded posterior extension. Egerton Coll. 
P. 2845 c. Low-crowned posterior tooth, shown, of twice the 
natural size, in PI. XI. fig. 7; Stonesfield. The lateral 
cones are relatively broader and apparently more rounded 
than in the principal teeth. Enniskillen Coll • 
P. 2845 d. Imperfect tooth ; Stonesfield. Enniskillen Coll. 
Hybodus grossiconus, Agassiz. 
1843. Hybodus yrossiconus , L. Agassiz, Poiss. Foss. vol. iii. p. 184, 
pi. xxiii. figs. 26-41 (P fig’. 25). 
1858. Hybodus yrossiconus , F. A. Quenstedt, Der Jura, p. 348, pi. 47. 
%• 33 . 
(?) 1858. Hybodus monoprion, F. A. Quenstedt, op. cit. p. 348, pi. 47. 
figs. 31, 32. 
1871. Hybodus yrossiconus , J. Phillips, Geol. Oxford, p. 177, diagr. 
xxxvii. figs. 4-6. 
(?) 1875. Hybodus polyprion, K. Fricke, Paheontogr. vol. xxii. p. 393, 
pi. xxi. figs. 17, 18. 
Type. Detached teeth ; School of Mines, Paris ; British Museum ; 
and Caen Museum. 
Teeth with a very high, much compressed crown • median cone 
very broad and nearly erect in the large principal teeth, narrower 
in the smaller teeth ; lateral cones two or three in number, narrow 
and sharply pointed. Coronal surface marked by numerous deli¬ 
cate vertical wrinkles, extending to the apices in the lateral cones, 
but only reaching the apex of the median cone in the hinder small 
teeth. Root antero-posteriorly compressed. 
