1903.] ^<y> North American Cretaceous Fishes. 63 



much like that of Tarpon, but the precoracoid is larger than 

 in the latter genus. On the other hand, it is smaller than in 

 Portheus. In the specimen under consideration it is about 

 125 mm. long. The shoulder girdle is here illustrated from 

 a rough sketch. 



On Plate III, Fig. i is shown a view of the tail of this species 

 taken from No. 1900 of the American Museum. The tips of 

 the lobes are broken away so that the original dimensions 

 cannot be known, but the lobes are now respectively about 

 265 mm. and 335 mm. in length. There is a large terminal 

 fan-shaped bone, which supported the principal rays. On 

 each side there is a triradiate bone, apparently a modified 

 ray, lying on the terminal vertebral bodies. Ryder (Report 

 U. S. Fish. Com. for 1884, pi. vi, fig. 2) has figured a similarly 

 placed bone which he regards as growing out from a displaced 

 epural. In front of the lower lobe of the fin of Pachyrhizodns 

 here described is an excavation which probably has been 

 occupied by a lunate bone such as that referred to above as 

 being found in the specimen at Washington. Fig. 2 of Plate 

 III shows a nearly complete lobe. Its length is 435 mm. 

 In these fins the rays are few in number, large, and cross- 

 segmented. The fin resembles considerably that of Tarpon. 

 Its number is 1658. 



Dr. Loomis has described a species which he calls P. curva- 

 tus. It is small, the tooth line of the dentary measuring only 

 50 mm. In this space are alveoli for 38 teeth. The maxilla 

 possessed alveoli for 41 teeth. The species appears to the 

 present writer to be a young individual of P. caniniis. In 

 the type jaw of P. caniims are spaces for 38 or 40 teeth, and 

 in a maxilla I count at least 40 teeth. Professor Cope re- 

 garded this fish as probably a ground feeder, but the form 

 of the tail seems to indicate a swift, free-swimming, predaceous 

 animal. 



No. 2041 of this Museum consists of 9 caudal vertebrae 

 and apparently 15 rays of an unpaired fin. There can be 

 little, if any, doubt that the fin belongs with the section of the 

 vertebral column, but whether it is the anal or the dorsal 

 cannot be ascertained. The longest rays measure 147 mm. 



