IS FOSSIL REPTILIA OF THE 



length, and 1 inch in basal breadth ; is sub-depressed, and curved downward. About 

 3 lines in advance of the joint, its breadth is increased by two lateral ridges. The 

 apex is subacute. The under surface is marked by many fine, wavy ridges. There 

 are two obtuse longitudinal prominences on the under surface near the joint, for 

 the advantageous insertion of the flexor tendons, and there is a rough prominence 

 at the middle of the dorsal surface, near the joint for the insertion of the extensor 

 tendon. The dorsal surface near the margins and apex, is sculptured by vascular 

 grooves. The total length of the first digit (i) is 6 inches. 



The second metatarsal (ib., a) is 5 inches in length ; with a proximal articular 

 surface 1 inch 6 lines in breadth, sinuous but almost flat; this surface presents 

 almost double the transverse extent in the antero-posterior direction. The inner and 

 anterior part of this surface is produced inward, or tibiad, apparently to afford an 

 abutment or attachment, at least in part, to the proximal end of the first metatarsal. 

 The outer or fibular side of the second metatarsal is almost straight, the inner or 

 tibial one concave, the expansion at both ends taking place chiefly in that direction. 

 The distal articular surface is convex from before backwards, with a median groove 

 producing a transverse concavity between the two convexities or condyles, at the 

 posterior half; and these slightly project backward. The first phalanx of the 

 second toe is 1 inch 3 lines in length, 1 inch 7 lines across the proximal, and 1 

 inch 6 lines, across the distal end ; the diameter from before backward at the 

 middle of the shaft is 6 lines, the phalanx is consequently broad and sub-depressed. 

 The posterior or plantal surface at the proximal end is slightly produced. The 

 distal articular convexity extends a little way upon the middle of the dorsal 

 surface, and slightly swells out into two condyles at the opposite surface. The 

 second phalanx is much shorter in proportion to its breadth, which at the base is 

 1 inch 6 lines ; the length being 1 inch 7 lines ; the tibial border is short and con- 

 cave ; the fibular one is straighter and one third longer. The ungual phalanx (») 

 differs chiefly from that of the first digit in its superior size, being 2 inches in 

 length and 1 inch 4 lines in its greatest breadth ; the fibular margin is convex, 

 the tibial one slightly concave. A side view of the bone, of the natural size, is 

 given at fig. 4, Tab. X. 



The length of the third metatarsal (ib., ui) is 5 inches 4 lines. It is more sym- 

 metrical in shape than the rest. The transverse breadth of the proximal end is 

 1 inch 8 lines ; the fore and aft breadth is 2 inches 1 line. The thickness in this 

 direction diminishes rapidly towards the distal end ; the transverse dimension 

 decreases in a much less degree ; this, at the middle of the bone, being 1 inch 2 

 lines, whence it increases to a distal transverse breadth of 1 inch 1 1 lines. The 

 configuration of this articular surface resembles that of the second metatarsal; the 

 fore and aft breadth of the condyle is 1 inch 6 lines. The proximal phalanx of 

 the third toe (ib., m, l) is 1 inch 2 lines in length, 1 inch 10 lines across the base, 



