74 



arc considerably constricted medially. Those of one series are square in 



section; those of another, transverse; those of a third, transverse, with one 



edge thinned or acuminate in section. Some of each form are more elongate 



than others. 



Measurements. 



Inches. 



Width of the femur at tho extremity (restored) 8. 



Depth of the femur at the extremity (median) 1.3 



Width of the femur four inches from the extremity 6. 



Thickness of the femur four inches from the extremity 1.95 



Width of tho tibia 3.88 



Length of the tibia externally 2. 6 



Width of tho tarsi (tibial) 2.48 



Thickness of tho tarsi (tibial) 1.52 



Length of tho parallelopiped phalange 1.56 



Width of the parallelopiped phalange 1.2 



Thickness of the parallelopiped phalange 1.2 



Thickness of the depressed phalange 1. 



Width of the depressed phalange 1. 4 



Length of the depressed phalange 1.9 



These powerful extremital pieces indicate a body to be propelled of not 

 less than usual proportions. If this be the case, the number of dorsal verte- 

 bra? is considerably greater than in the species of this order in general, and 

 approaching more the Ichthyosauri. I do not intend to suggest any affinity 

 between the latter and the present genus, as none exists. What the extent 

 ol the cervical vertebras may have been is uncertain. The caudals have prob- 

 ably been numerous, though not probably so extended as in E/as»iomurus. 



The size of the species may be approximately estimated from the pro- 

 portions furnished by Owen (Reptiles of the Liassie Formation) in Plcsio- 

 saurus rostratus. The skeleton of this species measures 11 feet 8 inches in 

 length, and the dorsal vertebrae are of less vertical and equal transverse 

 diameter compared with those of the present saurian. We may, therefore, 

 suppose that the latter exceeded the former in dimensions. 



William E. Webb, of Topeka, discovered the specimens from which this 

 species was first described, and liberally forwarded them (o me for examina- 

 tion and description Other specimens have been discovered since that time 

 by various other persons. I have received numerous fragments of an individ- 

 ual of about the size of the one above described, which were found by Prof 

 B. F. Mudge, a1 a point near the mouth of the north branch of the Smoky 

 Hill River. 



These consist of a few vertebrae, portions of pelvic and scapular arches, 

 and three proximal bones of the limbs. Which of these is femur and which 



