Cope.] "^^ [May 6, 1870. 



As to geological age, the indications are rather more satisfactory. The 

 genus Clupea ranges from the upper Eocene upwards, being abundant in 

 the slates of Lebanon and Monta Bolca, while Cyprinodon has been found 

 in neither, but first appears in the Middle or Lower Miocene in Europe. 

 The Asineops resemble very closely, and I believe essentially, the Pygeaus 

 of Agassiz, of Eocene age, from Monta Bolca. The peculiarities pre- 

 sented by the genus found by Dr. Hayden, are of such small significance 

 as to lead me to doubt the beds in question being of later than Eocene 

 age; though the evidence rests chiefly on this single, new and peculiar 

 genus. 



The position of these fishes, 7000 feet above the level of the sea, fur- 

 nishes another illustration of the extent of elevations of regions once con- 

 nected with the ocean, and the comparatively late period of Geologic time 

 at which, in this case, this elevation took place. 



Supplementary Notice op a new Chim^rid prom New Jersey, 

 Leptomyltjs cookii. Cope. 



Indicated by a right inferior maxillary bone, of one-fourth the size of 

 that indicating the Leptomylus densus. In general form the ramus re- 

 sembles that of Ischyodus divaricatus, the posterior portion being curved 

 outwards from the sympliyseal. The latter region is much compressed 

 and moderately prolonged, the inner face quite concave ; posteriorly the 

 outer face is also slightly concave. There is a single external crest, which 

 is obtuse, and descends gradually to the plane of the beak, and presents 

 no dentinal area. A single small oval area represents the internal, so large 

 in Ischyodu.s. It lies along the inner margin. This margin is much 

 thickened, and rolled over inwards ; sympliyseal face very narrow. The 

 extremity of the beak is broken away, and the section shows that there is 

 no inferior plate-like column, which produces the terminal area in most 

 species of Ischyodus, but a round column, which issues on the upper sur- 

 face of the beak, behind the apex. 



Lines. 



Depth at posterior margin outer crest 25.4 



" " anterior base " " 15. 



" " end terminal column 6.8 



Width of inner area 2. 



" at " " 10.6 



" " middle of beak 5.4 



The apical dentinal column of this species distinguishes it from the L. 

 densus. Cope, where no such column exists. It may be noted that at the 

 posterior fractured section of the jaw, the apical column is seen, while in- 

 ternal dental area is not, the latter occupying only a pocket, not a column. 



This species approximates Ischyodus solidulus in the apical column, 

 which has the same form in both. The two dentinal faces the latter pos- 

 sesses, are those of true Ischyodus. 



From the upper marl bed of the Cretaceous of New Jersey, from near Mt. 

 Holly. Dedicated to Prof. Geo. H. Cook, under whose auspices the palse- 

 ontological intei-ests of the State survey have been extended. 



