Teeth of new CMmceroid Fishes. 15 



oral border scarcely sitmous ; the symphjslal, median, and 

 posterior outer tritors deep and narrow ; anterior outer tritor 

 absent. [Palatine and vomerine teeth unknown.] 



Remarlcs. — This genus is founded on the form of mandi- 

 bular tooth recorded in the British Museum Catalogue (pt, ii. 

 pp. 551, 552) as possibly referable to very young individuals 

 of Ischyodus Beanmonti. The diminutive specimens from 

 the Kimmeridge Clay of Weymouth noticed in that work did 

 not seem to justify the foundation of a distinct genus and 

 species; but a nearly similar mandibular tooth measuring 

 0*033 m. in length, now available in the Leeds Collection, 

 shows that the fossils in question truly pertain to a hitlierto 

 unknown fish. In general outline they are most closely 

 similar to the mandibular teeth of Ischyodus Dufrenoyi. 



Brachymylus altidenSj sp. n. 



Diagnosis. — Mandibular tooth about as deep as long, with 

 a regularly excavated sharp oral border and short beak ; 

 post-oral margin parallel with the symphysial ; beak-tritor 

 and posterior outer tritor very small ; median tritor occupying 

 less than one third of the length of the oral face and situated 

 in its hinder half. 



Remarhs. — This species is known only by the left 

 mandibular tooth, which measures 0'033 m. in length and is 

 complete with the exception of the tip of the beak. The oral 

 border of the tooth is very sharp and dense, but there is no 

 conspicuous strengthening layer on the outer face. 



Formation and Locality. — Oxford Clay, Peterborough. 



Brachymylus minor^ sp. n. 



Diagnosis. — Mandibular tooth with a very slightly exca- 

 vated, somewhat wavy, sharp oral border and insignificant 

 beak ; post-oral margin parallel with the symphysial, and its 

 length much exceeding the antero-posterior measurement of 

 the tooth ; all the tritors small, the median tritor occupying 

 less than one third of the oral face and situated in its hinder 

 half. 



Remarhs. — The three teeth thus described (Brit. Mus. 

 nos. 41866-67) differ from the corresponding tooth of the 

 type species in the comparative straightness of the oral border 

 and the relatively great length of the post-oral border. They 

 are also distinguished by their very small size, the antero- 



