﻿70 CTTm^ROIDET. 



Ischyodus latus, Newton. 



1878. Ischyodus latus, E. T. Newton, Chimaeroid Fishes Brit. Cret. 

 Rocks (Mem. Geol. Surv.), p. 32, pi. x. figs. 1-3 (Pfigs. 4-] 2). 



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. Sf 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 , 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. Sf 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. Robert Marsham, 1877. 



The following dorsal fin-spines are of the form named Leptacan- 

 thus by Agassiz, Aiduxacanthus by Sauvage, and Chimceracanthus by 

 Quenstedt, and probably all pertain to species of Ischyodus : — 



32728-30. Three imperfect spines of the form named Leptacanthus 

 longissimus, Agassiz 1 , and probably referable to Ischyodus 

 emarginatus ; Great Oolite, Caen, Normandy. Tesson Cull. 



1 Poiss. Foss. vol. iii. (1837), p. 29, pi. i. a. figs. 14-18. 



