Stewart.] Cretaceous Fishes. 371 



heads where they articulate with the fin, and they probably 

 have similar expansions at the other extremity. 



P. agilis. P. nitida. P. ylarfiits. 



Length of spine fragment 360 mm. 705 mm. 1,040 mm. 



Width at base 62 " 67 " 120 " 



Thickness at base 6 " 12 " 



The spine mentioned above, and thought to be pelvic, is about 

 the size of the one described above, but differs from it in having 

 the anterior border nearly straight, without the undulations, 

 and but very little of the enamel-like deposit mentioned above. 

 At the base of the spine there is a mass of bone which presents 

 a large, liat articular surface, above and in front of which there 

 is a large, pointed process of bone extending upward from the 

 base of the anterior border. The spine is probably more narrow 

 than the one just described. 



Length, apex wanting 428 mm. 



Width near center 45 " 



Width at base (estimated). 53 " 



Long diameter of condyle at base 31 " 



Short diameter of condyle at base 21 " 



I am unable to say to what species the pelvic fin-spine, de- 

 scribed above, may belong. It is of a different individual from 

 the pectoral spine described as belonging to P. penetrans, but 

 for the present, at least, I will consider it under this head. 



CLUPEIDiE. 



The family ffalecida '-' was made by Agassiz to include the 

 two families Salmonida and Clupeidse, fossil specimens often 

 being so closely related to both of the above families as to ren- 

 der their exact relation to either of the above two families some- 

 what doubtful. 



The tendency among ichthyologists seems to be to revive the 

 two old family names ; thus I use the name Clupeida to include 

 the single genus Leptichthys, which seems to bear a close rela- 

 tionship to this family in many respects. 



Am. Geol.. vol. XXIV. pp. 78, 79. 



