70 
CHIM^SEOIDET. 
Ischyodus latus ? Newton. 
1878. Ischyodus latus, E. T. Newton, Chimseroid Fishes Brit. Cret. 
Rocks (Mem. Geol. Surv.), p. 32, pi. x. figs. 1-3 (Pfigs. 4-12). 
Type. Mandibular tooth; Museum of Practical Geology. 
Mandibular tooth closely resembling that of I, thurmanni , but the 
median tritor very broad and extending forwards to the symphysis. 
Supposed palatine tooth with very broad tritors covering nearly the 
whole of the oral surface, the outer tritor being narrow, and the 
median extending further forwards than the posterior inner tritor. 
Form . &f Log. Cambridge Greensand : Cambridge. 
Not represented in the Collection. 
Ischyodus (?) incisus, Newton. 
1878. Ischyodus incisus, E. T. Newton, op. cit. p. 38, pi. xii. figs. 3-10. 
Type. Left mandibular tooth ; British Museum. 
A small species of doubtful generic position, the mandibular tooth 
apparently not attaining a greater antero-posterior measurement 
than 0*035-0*04. Mandibular tooth much compressed, with a deeply 
sinuous oral margin, acute eminences corresponding to the outer 
tritors, and the beak prominent; post-oral margin partly parallel 
with the symphysial margin ; beak-tritor subdivided into a short 
series ; anterior outer tritor small and narrow, the posterior one 
represented by a marginal series of minute tritors; median tritor 
very narrow and insignificant. [Palatine tooth unknown.] (?) Vo¬ 
merine tooth relatively broad, prominently convex externally. 
Form. $ Log. Albian: Kent. Cenomanian: Cambridgeshire. 
Turonian : Kent and Sussex. 
41683. Left mandibular tooth, being the type specimen figured by 
Newton, op. cit. pi. xii. figs. 3-5; Lower Chalk, (?) Kent. 
Toulmin-Smith Coll. 
47942-3. Left mandibular and vomerine teeth, figured by Newton, 
op. cit. pi. xii. figs. 6-8 ; Lower Chalk, Burham, Kent. 
Presented by the Hon. Pobert Marsham , 1877. 
The following dorsal fin-spines are of the form named Leptacan- 
thus by Agassiz, Auluocacanthus by Sauyage, and Ohimcer acanthus by 
Quenstedt, and probably all pertain to species of Ischyodus :— 
32728-30. Three imperfect spines of the form named Leptacanthus 
longissimus , Agassiz \ and probably referable to Ischyodus 
emarcjinatus ; Great Oolite, Caen, Normandy. Tesson Coll. 
1 Poiss. Foss. vol. iii. (1837), p. 29, pi. i. a. figs. 14-18, 
