287 



narrow border rises abruptly opposite the middle of the anterior area, causing 

 the masticatory face to be very oblique at that point. The outer face of the 

 jaw exhibits two longitudinal convexities, and the inner is nearly vertical, and 

 with a short symphyseal plane. The beak is narrow and produced. The. 

 maxillary bones which accompanied the type-specimens are of usual charac- 

 ter. The dentinal areas are large, and the anterior border not much pro- 

 duced. Superior groove wide; outer face not produced. 



Measurements. 



M. 



Total length °- 175 



Depth behind 0-090 



D.-pth at the posterior outer area 0. 0S0 



Depth at the anterior outer area 0. 055 



Length to the anterior outer area 0. 075 



Width at the anterior outer area 0. 038 



Width at the iiuer angle behind 0.033 



Width at the middle of the beak 0. 020 



The type-specimens of this species came from the upper bed of green- 

 sand at Hurffville, New Jersey. It includes both mandibles and the left max- 

 illary bone. Specimens agreeing with these in all respects are not uncom- 

 mon. 



IsCHYODUS LONGIROSTR1S, Cope. 



With this species, we enter the more typical group of the genus. The 

 form of the / longiroslris is much that of the I. fecundus, but is characterized 

 by a considerably greater anterior prolongation, and by the narrowing of the 

 inner area, so as to leave a wide oblique plane between it and the inner angle 

 of the jaw. The outer posterior area is lost from the specimen, but the outer 

 anterior opens in front of the interior on a horizontal step, which forms a 

 strong angle of the outer border. This border is, therefore, abruptly exca- 

 vated from that point forward, while the inner border descends gradually 

 from the inner angle. The terminal area is quite large and oblique. The 

 symphyseal face is large, and the inferior border of the jaw obtuse, while the 

 end of the jaw is narrowly compressed. 



Measurements. 



it. 



Total length 0.112 



Depth at the anterior outer area t o. 053 



Depth at the middle of the beak 0. 020 



Width at the middle of the beak : 0. 017 



Width at the angle behind 0.033 



Width of the inner area 0.015 



