364 



THE PORTLAND OOLITE PERIOD. 



CHAP. 



These drawings are from casts of the specimen described by 

 Professor Owen. 



Length, 12*4 inches ; breadth at the distal extremity, 5*8 ; depth 

 of the same, 2-3 ; diameters of the head, 4-0 by 3-3 ; a prominent 

 half-encircling wrinkled and pitted ridge, three inches on the inside 

 below the head. The distal articulating face is a little concave 

 anteriorly, convex posteriorly. Some specimens are 16 and 18 inches 

 long. From Shotover. 



Diagram CLXII. Humerus of Pleiosaurus (?) trochanterius. Owen. Scale 

 one-tenth of nature. 



Length, 24 inches ; breadth of the distal end, 10 ; depth of the 

 same, 2 ; diameters of the proximal end (bicipital), 6 and 5 ; of the 

 shank where smallest, 4. 



The head is remarkable for the great size of a trochanterial 

 projection, which rises higher than the proper articulating head 

 on the exterior side, and is separated from it, somewhat as the great 

 trochanter of iguanodon is outstanding. On the inner side is a 

 wrinkled surface below the head. 



The bone grows thinner and wider toward the distal end, where 

 two excavated articulating faces appear, each marked by a longi- 

 tudinal median prominent ridge. These faces meet to constitute 

 a very distinct transverse salient keel. 



The cast of the specimen described by Professor Owen d agrees 

 with specimens not so large from Wheatley and Foxcombe, ex- 



d See note as to the locality, p. 316. 



