BRITISH FOSSIL REPTILES. 115 



the long diameter is 8 inches 4 lines, the short or transverse 

 diameter 6 inches. 



In the British Museum the scapulae of an Ich. platyodon are 

 preserved, each measuring 1 foot 5 inches in length, and 9 inches 

 in breadth at the distal end. 



The humerus is as short in proportion to its breadth as in the 

 preceding species, but is more concave anteriorly than in the 

 Ich. communis or inter medius\ Its proximal rounded extremity 

 is tuberculated at its circumference, and the shaft is grooved 

 superiorly. 



This character of the concavity or emargination of the ante- 

 rior edge of the bone is present in a more marked degree in the 

 radius or the anterior of the two bones which succeeds the hu- 

 merus, and neatly distinguishes it from the corresponding bone 

 of the Ich. com7nunis or intermedins. There is no sufficient 

 distinguishing character in the ulna, which diflPers only in size 

 from that of the other Ichthyosauri, 



The rest of the anterior paddle is composed of small trans- 

 versely oblong bones, which gradually diminish in size to the 

 extremities of the digits ; and the limits of carpus and meta- 

 carpus can only be arbitrarily defined as in the other Ichthyo- 

 sauri. The first or carpal row consists of three bones, as in the 

 Ich. intermedins, but the radial or anterior ossicle is distinguished 

 in the Ich. j)latyodon by an anterior emargination corresponding 

 with that of the radius above. The same character is presented 

 by the corresponding bone of the succeeding series, beyond 

 which it is lost. 



The whole paddle is not less clearly characterized, than the 

 individual bones above mentioned, by the comparative paucity 

 of its digital subdivisions ; these do not exceed three in number, 

 with two or three small supplementary ossicles on the radial 

 margin of the paddle, which may be regarded as the rudiment 

 of a fourth digit. The component phalangial ossicles are more 

 rounded in their contour, and less transversely elongated, than 

 in the previously described species : their margin is slightly 

 raised on the outer surface. Beyond the antibrachium I count 

 fourteen ossicles in each of the marginal, and fifteen in the me- 

 dian row, which, with the three supplementary ossicles, make 

 forty-seven in the whole fore paddle or manus. 



The pelvic bones are characterized by their relative superiority 

 of size, more especially the ilium. 



The femur, together with the other bones of the posterior 

 member, is still longer in proportion than in the other species 

 of Ichthyosaurus. It is only a very little less than the humerus : 

 its proximal extremity presents a large depression, probably for 

 the attachment of a stout ligament. 



The tibia presents the same anterior emargination as the cor- 

 I 2 



