366 THE PORTLAND OOLITE PERIOD. CHAP. 



diameter of the proximal end, 4-2. A smooth almost straight-sided 

 bone regularly expanding from the upper part. From Swindon. 



Diagram CLXV. Femur of Pleiosaurus simplex. Scale one-tenth of nature. 



Length, 16 inches; breadth of distal end, 7-6; diameter of head, 

 4-0 ; of shank where least, 3-5. This is a smooth bone with little 

 mark of tendinous attachment. From Shotover. Specimens only 

 half or even one-third of this size occur in the Coralline oolite and 

 Oxford clay. 



PLESIOSAURUS AFFINIS. Owen. 



Under this head Professor Owen describes a femur from Shotover 

 Hill as like P. trochanterius, but smaller, and with a less prominent 

 trochanter. There is a transverse rugosity on the inner side of the 

 upper fourth of the bone. In this it resembles P. grandis. Its 

 length is 8 inches. 



PHALANGAL BONES OF PLEIOSAURUS. 



Phalangal bones occur in considerable number, but it is rarely 

 the case that they can be obtained in such a manner as to admit 

 of being replaced in their true relative situation. It is for the most 

 part uncertain to what species they belong. Only one specimen 

 has yet occurred that from Market-Rasen which presented no 

 difficulty in this respect. The large bone represented in Diagram 



