136 



CRETACEOUS AND TERTIARY FISH. 



Fig. 84. — Isotcenia neocasariensis Cope. (Type, from Hussakof.) 



Hornerstown in Monmouth County (J. G. Miers), and now in 

 the American Museum at New York. I have not seen this speci- 

 men. 



Genus LEPTOMYLUS Cope. 



Leptomylus Cope, Proc. Boston Soc. N. H., XII, 1869, p. 313. Type Lepto- 

 mylus densus Cope, monotypic. 



This genus is related to Psaliodus Egerton, 1 differing in hav- 

 ing a single small, narrow dentinal area near the inner margin 

 of the mandibular, which is also without any symphyseal bevel. 

 Median interior longitudinal ridge obtuse and little marked, 

 coated with dense glossy layer. 



Species 3, all extinct. 



1 This genus shows no dentinal areas in the mandibulars. 



