290 



ISCHYODUS GASKILLII, Cope. 



This Chimasroid makes a nearer approach to the species of Diphrissa 

 than any other member of this genus. This is seen in the very small size 

 of the external dentinal columns; especially of the posterior, which is not 

 only small but shallow. The anterior is oval, within the outer border, and 

 not on a tuberosity ; its anterior border is considerably beyond that of the 

 inner area. The latter is rather narrow and oblique, extending to the inner 

 border of the jaw, and leaving a wide band between it and the outer. The 

 inner and outer borders of the beak are continuous, and not abruptly exca- 

 vated ; but the outer rises considerably higher posteriorly, carrying the solid 

 upper surface as a narrow plane horizontal in transverse section. The inner 

 face is gently concave, with very slight symphyseal bevel ; the outer mostly 

 concave, so that the lower border is quite narrow. The long axis is regularly 

 curved outward. The terminal area is less narrowed than usual, the column 

 being a cylinder, with a narrow superior lamina. 



Measurements. 



M. 



Total length -. 0.077 



Depth at the posterior outer area 0.040 



Depth at the anterior outer area - 0.025 



Depth at the middle of the beak 0.013 



Width at the middle of the heak 0.010 



Width at the posterior outer area 0. 0S0 



Width of the inuer area 0. 015 



Greensand of New Jersey, No. 5. From the marl-pits of Judson Gaskill. 

 at Birmingham, a locality which, through the interested cai-e of the proprietor, 

 has yielded many important additions to paleontology. 



ISCHYODUS FECUNDUS, Cope. 



A large species, second in the genus to the I. tripartihis. Both the inner 

 and anterior outer dentinal areas are narrowed anteriorly, and they terminate 

 on the same transverse line. The. anterior outer is rather small and wide, 

 and is horizontal, so that the apex is elevated abruptly above the outer border 

 of the beak ; but not to the same extent as is seen in I. smockii, nor are the outer 

 areas elongate, as in that species. The present fish is also twice as large. 

 The inner border of the beak has the same abrupt descent as the outer. This 

 form distinguishes it from I. mvrificus. The posterior outer area is rather 

 small, while the inner is large. The long axis is strongly curved, and the 



