1869.] 313 [Cope. 



than in any other species; those of the latter are much narrower and 

 deeper than the P. hrachyodon, and decurved. 

 Leptomylus deusus Cope, genus et species novte Chimeridarura. 

 This species appears to be intermediate between Psaliodus Egert. , 

 and the other genera of Chimerklce. While that genus does not 

 exhibit dentinal tubercles on the inferior maxillary bones, the pres- 

 ent has but one, which is small and narrow, and near the inner 

 margin of that bone. The other bones of the anterior cranial arches 

 are not yet known. The structure of the bone is more dense than in 

 the other forms known to me. The extremity of the element is 

 broken, but the inner margin does not exhibit any symphyseal bevel, 

 where it occurs in the species of Ischyodon. The median interior 

 longitudinal ridge is obtuse and little marked, and coated Avith a 

 dense glossy layer. 



Char, specif. Anterior extremity prolonged, and slightly narrowed. 

 The posterior face is plane, transversely concave longitudinally. 

 When the external margin rises, the internal falls off, and the narrow 

 area of dentine is directed obliquely upwards and inwards. The 

 inner face, above an anterior thickened margin as deep as the pro- 

 longed beak, is concave, but is again convex near the superior margin. 

 It is marked with coarse and obscure curved lines, which are parallel 

 to the posterior outer margin. The inferior or anterior margin is a 

 contracted ridge, its inner plane vertical, while the superior part of 

 the inner face expands inwards. The dentinal column supporting the 

 tubercle is as large as a goose quill. There are no other columns. 



Lines. 



Depth one inch behind tubercle 50.25 



Depth at middle of jaw 26.2 



Length from first point 65 



Added for lost apex 14 



Length of tubercle 7.1 



This species is the largest Chimaji'oid fish yet discovered in North 

 America, and equals the large Ischyodus Toionsendii of Egerton, from 

 the Portland stone of .Great Britain. 



This species was procured by the ^vriter from Judson Gaskill, one 

 of the directors of the Birmingham Cretaceous marl pits. New Jersey, 

 where the specimen was found. 



During the same season, and at the same place, but some weeks 

 anterior to that of the specimen just described, a superior max- 

 illaiy was found, which may belong to the same species. It indicates 

 also a genus distinct from any known. Its general features are those 



