a Pachypod from the Cambridge Upper Oreenaand. 311 



slightly concave. The whole surface seems to be laterally 

 oblique to the shaft of the bone, being inclined towards meta- 

 podial bone no. 1 ; it is not so flat as the corresponding surface 

 in no. 1, being slightly convex both in breadth and length. 



The bone contracts between the proximal and distal articular 

 ends, and in the middle of the shaft measures 1^ inch from 

 side to side, and 1| inch from above downward behind the 

 distal articulation. The lateral and upper and under surfaces 

 are all concave in length. The lateral side towards bone 1 is 

 flat, vertical at the two ends, and very slightly convex in the 

 middle. The lateral side towards bone 3 is concave vertically 

 at the proximal end, flat in the middle, where it apj^roximates 

 on the under surface towards the other lateral side, and flat at 

 the side of the distal articulation ; all these parts are in diflerent 

 planes. The superior surface is convex ; it is obliquely in- 

 clined towards bone 1 at the proximal end, and less inclined 

 towards bone 3 at the distal end. The under surface contracts 

 so as to measure about | of an inch from side to side in the 

 middle ; at the two ends it is concave from side to side. The 

 distal end is subreniform in outline, being convex above, con- 

 cave below, and flattened or slightly convex at the sides. It 

 measures 2^ inches from side to side, and more than 2 inches 

 from above downward ; it is regularly convex from above 

 downward ; and toward the under half a median depression 

 appears and continues increasing in concavity. The articula- 

 tion does not make quite a right angle with the shaft, being a 

 little inclined towards the first metapodial bone. 



In the third bone the proximal and distal ends are less ex- 

 panded than in the second bone, so that its aspect is more 

 slender ; it measures 6 j inches in length. The proximal arti- 

 culation is more quadrate than in the second bone, measuring 

 about 2 inches from side to side, and 2| inches from above 

 downward ; it is set on to the shaft with an obliquity like that 

 seen in the second bone, and similarly has the two pairs of sides 

 parallel and the sui-face convex. The side towards the second 

 bone is very convex, an inflation running down the middle of 

 the side, and dying away towards the condyle of the distal 

 articulation. Proximally the side of the bone looks as though 

 slightly compressed in fossilization ; distally the side is flat. 

 All the sides are concave in length, the upper one least so. 

 The side towards bone 4 is smooth and flat, and inclines in- 

 feriorly towards its opposite side, so as only to be divided 

 from it below by a rounded ridge. The upper sui-face is better 

 defined than in the other bones described; it is concave from 

 side to side behind, and convex from side to side in front. 

 The shaft measures from side to side in the middle 1^ inch, 



