No. I.] 



THE GENUS OE FOSSIL EISHES. 



39 



able patch of small teeth on the entopterygoid (Fig. 7, /.), and 

 another smaller patch on the ectopterygoid (Fig. 7, t}). In the 

 Tarpon teeth occur on the vomer, parasphenoid, pterygoids, 

 and even on the quadrate. 



The hyomandibular (Fig. 7, km) is in many respects like 

 that of Tarpon, but, like the other bones of the extinct genus, 

 is of more massive construction. The anterior border of the 



>jnx. art. 



Fig. 7. — X. t/innj?ias. Hyomandibular and palato-pterygoid bones, x |. 



bone extends further forward than it does in Tarpon. In the 

 latter the anterior border falls, with a sigmoid curve, in a 

 general downward direction, crossing the posterior angle of 

 the metapterygoid. In Xiphactinus the anterior border of the 

 hyomandibular runs rapidly forward, so as to come into contact 

 with and pass mesiad of the posterior border of the entoptery- 

 goid. The greatest width of the hyomandibular from the 

 articulation of the operculum to the anterior border is nearly 

 equal to the distance from the anterior border to the anterior 

 end of the palatine. In Tarpon the latter distance is about 

 2.5 times the greatest width of the hyomandibular. However, 



