﻿LIASSIC FORMATIONS. 



31 



opposite margin of the ulna is very convex ; the distal end is divided by a low angle 

 between the surfaces for the outer and middle carpals of the proximal row. 



The carpal bones are six in number, three in each row. The proximal ones are 

 the largest, but, of this row, the radial carpal, or ' scaphoid,' is least ; it is of a trans- 

 versely oblong figure, with its distal border divided by a low angle between the radial 

 and the middle bones of the second row ; this relation is better shown in the right 

 than in the left pectoral fin. The middle proximal carpal, or ' lunare,' is the largest, of 

 a sub-hexagonal form ; the shortest side, toward the radius, is concave ; the side 

 opposite the radial carpal is rather convex ; the other facets for the ulna, ulnar carpal 

 (' cuneiforme') and the two larger carpals of the second row, are nearly straight. 

 The three carpals of the second or distal row increase in size from the radial to the 

 ulnar side of the waist ; the outermost being surrounded by three carpals and three 

 metacarpals ; the metacarpal of the fifth digit extending along its ulnar side to articu- 

 late with the ulnar carpal of the first row. In its relations to the metacarpals, the 

 largest of the second row resembles the ' magnum' and ' unciforme' combined, of the 

 mammalian carpus. The next in size answers to the ' trapezoides/ supports the second 

 metacarpal, and, at its opposite border, fills the interspace between the radial and 

 middle carpals of the first row. The radial carpal of the second row is the smallest 

 of all ; it is wedged between that of the first row, the first metacarpal and the middle 

 carpal of the second row : it answers to the ' trapezium/ 



The first metacarpal (ib., 56) is the shortest, 1 inch in length, it supports two 

 phalanges, the last of which is 1 lines in length ; the whole length of this digit, 

 including the metacarpal, is 2 inches. The second metacarpal is 1 inch 9 lines in 

 length, and supports six phalanges, the last being 4 lines long; the total length of this 

 digit, including the metacarpal, is 10 inches 6 lines. The middle metacarpal is 1 inch 

 10 lines in length, it supports eight phalanges ; the total length of this digit, including 

 the metacarpal, is 10 inches 6 lines. The fourth metacarpal is 2 inches in length, 

 it supports seven phalanges ; the total length of the digit, including the metacarpal, is 

 10 inches. The metacarpal of the fifth digit is 1^ inch in length, its proximal breadth 

 is 1 inch; that of the first metacarpal being half an inch, and that of each of the three 

 intermediate metacarpals ranging from 9 to 10 lines ; the outermost metacarpal sup- 

 ports seven phalanges : the total length of the digit, including the metacarpal, is 

 9^ inches ; the fifth metacarpal, besides being shorter and broader than the three 

 middle ones, is more convex, and obliquely bevelled off at its proximal end, the radial 

 side being shorter than the ulnar one. The phalanges of the fifth digit are more con- 

 cave at their outer or ulnar border than the others. The first metacarpal is more 

 concave at its radial border. All the phalanges are flattened and expanded at their 

 extremities, the outer surface showing linear impressions, the middle part being 

 smooth. The total breadth of the cai^pus is 4 inches 5 lines. The total length of the 

 hand is 1 foot 1 inch. The total length of the pectoral limb seems to have been about 



