I903-] 



Hay, North American Cretaceous Fishes. 



17 



that it represented a distinct species and to this he gave the 

 name Erisichthe dimidiata {Ptoc. Amer . Assoc . Adv. Sci., XXVI, 

 1878, p. 300). Of this change of opinion and this new- 

 name neither FeHx, writing in 1890, nor Looniis, writing in 

 1900, was apprised. 



The most obvious characters of the species are those 

 presented by Cope in his original description, the upward 

 curvature of the rostrum and the flattening of the upper 

 surface of its distal half. Felix, having before him a speci- 

 men which he regarded as belonging to the same species, 

 denies the presence of the angular ridges on the sides of the 

 rostrum. They are present, nevertheless. The rostrum (Fig. 

 8) has been broken across just in front of the vomerine fangs 

 and a portion of 

 the upper surface 

 has crumbled 

 away, perhaps for 

 a distance of 25 

 mm.; but there is 

 little or nothing 

 missing on the 



lower side. About Fig. S. Protosphyr<ena dimidiata (Cope). No. 1635. X s- 

 Ty^e oi Erisicktke diiitidtata Qo\>e Rostrum seen from the 



2 2 mm. in front side, with four cross-sections, rf/z., ethmoid ; Z't^w. ^., vomerine 

 teeth. 



of this break there 



has been another break and a slight faulting in the bone. 

 From this point there is a gradual upward curve to the 

 tip of the beak. Just in front of the last-mentioned break 

 the vertical diameter is 23 mm., the transverse, 26 mm., 

 the section being oval. Halfway to the tip, the upper sur- 

 face has become decidedly flat, the vertical diameter being 

 16 mm., the transverse, 22 mm. Beyond this section the 

 upper surface is somewhat concave, with a sharp ridge bound- 

 ing the concavity on each side. Near the tip the upper sur- 

 face again becomes convex. Both the upward curvature of 

 the beak and the concavity of the upper surface appear to 

 be wholly natural. 



There appears to be less difference in the sculpture of the 

 upper and lower sides than in the case of P. nitida. 



[ymiuary, fgoj.] 3 



