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



24 mm., and was in life probably somewhat more. The same 

 author has also stated that the superior surface of the skull 

 is swollen above the base of the great vomerine tooth, while 

 no such enlargement marks the position of its young com- 

 panion. This is readily explained. The downward crushing 

 during fossilization has been resisted by the base of the great 

 fang, while on the other side there has been nothing to resist 

 crushing. 



The vomerine fang referred to (Fig. i, vom. t.) has an 

 antero-posterior diameter of 17 mm. and a transverse diam- 

 eter of 8 mm. The crown is mostly missing. It has been 

 directed strongly forward. In the alveolus of the other side 

 is seen the tip of the fang which was to have come into func- 

 tion on the shedding of the large one now present. 



In 1890, Felix, as cited, identified correctly, as it appears, 

 and figured a beak as that of P. penetrans. 



Various other specimens which were collected for Cope in 

 1877, by Sternberg and Hill, are regarded as belonging to the 

 same species as P. penetrans and serve to throw light on its 

 relations to P. nitida. One of these, No. 1871, has been less 

 affected by pressure than any others of the collection. The 

 cross-sections of the rostrum are oval, with the transverse 

 axis the longer, until near the insertions of the vomerine 

 fangs, where the two axes are about equal. The ornamenta- 

 tion of the lower side is coarser than that of the upper, but 

 the pattern is the same. In this beak the left vomerine fang 

 is functional, while the right alveolus is a cavity 9 mm. deep. 

 The distance from the fangs to the tip of the rostrum is 125 

 mm.; the transverse diameter, 27 mm.; the vertical, 26 mm. 

 Halfway from the fangs to the tip the transverse diameter is 

 18 mm., the vertical, 15 mm. 



No. 2 1 21 of this Museum furnishes a complete beak, with 

 the base of the right tooth; the anterior end of the splenial, 

 freed from the dentary ; the tip of the left dentary with three 

 large teeth; some other fragments of the jaws and skull; and 

 three sections of the pectoral fin blade, measuring all together 

 250 mm. The beak is rather slenderer than the type of P. 

 penetrans and is smoother near the base. Sections of the 



