153 



M. 



Widtb of tho piemaxillary at tho seuond tooth I). 041 



Lcugtli of tho deutary 0. 2'ir> 



Lengtli of a luasillary tootb 0. OCO 



Length of tho maxilldiy tooth, crown only 0.023 



Length of the os quadratum 0. 077 



Width of the OS quadratum distally 0. 045 



Length of the parietal 0. 085 



Length of the frontal to the nares (median) 0. 110 



Width of thefroutal hetweeu the orhits 0.077 



Total length of the eranium (18.7r> iuches) U. 473 



Platecarpus crassaktus. Cope. 



This saiiriiui, which is of larger size than the last, is represented by a 

 series of dorsal, lumbar, and caudal vertebrEe, with some bones of the liinl)s 



The vertebrae are as much distinguished for liieir shortness as those 

 of P. lolisplnis are tin- their elongation. Tiie articular faces are but little 

 broader than dcej), and their planes are slightly oblique. They are very slightly 

 truncate aljove by tiie neural canal. The interior face is somewhat concave 

 in the longitudinal direction. The zygapophyses are stout, and there are no 

 distinct rudiments of zygosphen. 



The dorsal vertebrae best preserved are those in which the diapophyses 

 reach the middle of the sides of the centra, and have no horizontal limb. 

 The latter are luirrow, and have not extensive articular extrcmi'al siirliices. 



The lumbars and anterior caudals have round articular surfaces. One 

 of the latter, with strong diapophyses, but posterior, is subpentagonal in 

 outline of cup. 



This species furnished the materials for the first description of the 

 posterior extremities in this order of reptiles. The humerus is a remarkable 

 bone, having the outline of that of Clidastes irropython^ Cope, but is very 

 much stouter, the antero-posterior dimensions of the proximal extremity 

 being greatly enlarged. The long diameters of the two ('xtiemities are, in 

 fact, nearly at right angles, instead of in (he same plane; and the outline 

 of tlie proximal is subtriangular, one of the angles being prolonged into a 

 strong deltoid crest on the outer face of the bone, which extends half its 

 lengtii. The inner or posterior distal angle is nuicli produced ; while the 

 distal extremity is a flat, slightly-curved, diamond-shaped surface. The fibula 

 is as broad as long and three-quarters of a disk. The phalanges are stout, 

 thick, and depressed, thus differing much from those of Platecarpus ictericus. 

 A bone which I cannot assign tit any other position than that of femur has 

 20 c 



