1903] 



Hay, North American Cretaceous Fishes. 



bones within the mouth were furnished with small teeth, 

 but which they are has not been accurately determined. It 

 appears likely that the ectopterygoid 

 had minute teeth on its surface and some 

 larger ones near one border. 



I have had the opportunity of study- 

 ing No. 4186 of the U. S. National 

 Museum. In this the cleithrum has its 

 external face presented. The first ray 

 of the pectoral is segmented transverse- 

 ly, and was not a spine. Its anterior 

 border is furnished with square notches 

 and teeth, as is seen in Cope's work, pi. 

 Hi, fig. I. On lifting the cleithrum from 

 its bed the base of the fin is seen more 

 distinctly. Besides the first ray about 

 seven others are present. The precora- Fig. ^^. Empo nepahoUca 



. - Cope. No. 1969. X 3. Skull 



cold is present and is somewhat larger from below. <5.o<r., basiocdpi- 



tal ; ex.oc.y exoccipital ; /r., 

 than m a salmon which has a laW two- frontal: /«., parietal: pmx., 



ri^ii premaxilla ; //. o., pterotic. 



thirds as long as that of the fish here 



described. A portion of the coracoid is present and perhaps 

 some of the scapula. The presence of the precoracoid fixes 

 the position of the fish among the Isospondyli. 



In No. 4719 of the U. S. National Museum there is a series 

 of 25 vertebrae, together with ribs and the supports of the 

 pelvic fins. Of these, apparently 10 belong to the caudal 

 region, possibly only 9. Many ribs are present and several 

 of them in their natural relation with the vertebrae. They 

 are strongly developed, broad, and with much broadened 

 heads. They resemble those of the common carp. They have 

 been attached to distinct parapophyses. In some cases the 

 latter have been freed by maceration and disturbance, and 

 falling out have left long and deep cavities along the sides 

 of the vertebrae. The haemal arches of the tail region are 

 apparently consolidated with their corresponding vertebral 

 centra. 



The supports of the pelvic fins are preserved and a portion 

 of one fin (Fig. 72). It seems probable that the fin supports 



