8 Bulletin American Museum of Natural History. [Vol. XIX, 



obliquidens. The possession of five fangs in the premaxilla, 

 as in P . obliquidens, is unusual in Protosphyrcena, but when 

 we consider that the number of great fang-Hke teeth in the 

 jaws of Portheus varies, we shall not give too great value to 

 this character. In short, it appears to the writer that P. 

 obliquidens is identical with P. penetrans. Furthermore, it 

 seems impossible to distinguish these two nominal species 

 from Cope's P. nitida. 



No. 1634 is a part of the Cope Collection, and consists of a 

 considerable part of a crushed skull, with the basal half of 

 the rostrum. The axis of the skull is presented from the 

 vomerine fangs to the basioccipital articulation. A section 

 of the rostrum 52 mm. in front of the vomerine teeth is oval, 

 with the long axis transverse. At the vomerine teeth the 

 section is quadrate, but this is evidently due to lateral pres- 

 sure. The ornamentation is quite like that of the type of 

 P. penetrans, the base of the beak not being so smooth as in 

 No. 21 21. Seen from below, it much resembles that of P. 

 obliquidens. There is present a part of one of the pectoral 

 fins, presenting about 95 mm. of the edge, and this is identical 

 with that of No. 2121, and, so far as we may judge from the 

 figure, with that of P. obliquidens. But the latter has a com- 

 pressed section; No. 2 121, a depressed section. It appears to 

 the writer that the evidence furnished by the fins outweighs 

 that to be derived from the cross-sections of the rostra. 



Pelecopterus chirurgus was based on a part of a pectoral fin, 

 with the characteristic front edge broken away. Judging 

 from the part remaining, which comes up close to the edge, 

 and from the angle made by the rays with the edge, there 

 seems little doubt that this fin is identical with P. obliquidens , 

 and, therefore, with P. nitida. The specimen bears the Ameri- 

 can Museum of Natural History's number 1894. 



Under the name of Pelecopterus chirurgus Cope has de- 

 scribed (Vert. Cret. Form. West, p. 244E, pi. liv, fig. 9) the 

 articular portion of the shoulder girdle of another specimen. 

 There is no evidence that the latter belongs to the same 

 species as the type of P. chirurgus; and the specimen, which 

 is now in the American Museum, No. 1609, cannot be distin- 



