137 



" The ulna is very thin and flat, not quite so long as the humerus, 

 rounded slightly at its upper extremity, and still less at its lower 

 one. Its head has a cavity, which receives the posterior tubercle of 

 the humerus. Immediately inferior to this is a prominence on the 

 posterior margin, to which is attached the ligament of the two sesa- 

 moid bones. The superior ulno-radial joint admits of little motion, 

 being composed of a convex and plane surface. Near the distal ex- 

 tremity of the bone there are several rough lines for the attachment 

 of muscles. The distal articulating surfaces are three : one with 

 the radius anteriorly ; another with the first carpal bone inferiorly ; 

 and the third with the second carpal bone posteriorly and obliquely 

 downwards. 



" The radius much resembles the ulna in shape. At its head it 

 has two articulations : one superiorly, with the anterior tubercle of 

 the humerus ; and the other posteriorly, for articulation with the 

 ulna. There are likewise two articulations at its distal extremity : 

 posteriorly one for the ulna; and inferiorly there is another with the 

 first carpal bone. Near its neck is situated a process for the attach- 

 ment of muscles. On its superior anterior part a groove runs ob- 

 liquely, from before backwards, and from above downwards. At 

 the distal extremity there is a similar one, but running in a con- 

 trary direction, i. e. fi'om behind forwards. 



" The first carpal bone has the form of a trapezium, with three 

 articulating surfaces : a superior one for the radius ; a posterior one 

 for the ulna ; and an inferior one for the metacarpus. The shape 

 of the second carpal bone is triangular, with articulating processes, 

 and a notch on its inferior edge : one anteriorly for the ulna ; the 

 other inferiorly for the metacarpus. 



" The metacarpus is composed of a single bone, formed by the 

 union of two. The anterior of the two metacarpal bones supports 

 two phalanges of the first finger, and is twice the size of the posterior 

 one, which supports the single phalanx of the second finger. The 

 upper end is crescentic, articulated with the first carpal bone an- 

 teriorly, and with the second inferiorlj'. There is a sulcus between 

 the ends of the two bones, at their inferior extremity. 



" The first phalanx of the first finger is a long, broad, and flat 

 bone, tapering gradually from above downwards, united to the me- 

 tacarpus by a flat surface, and connected with the second phalanx 

 by a similar articulation. The other phalanx is broad and flat, ta- 

 pering from above downwards. By a similar articulation is attached 

 to the posterior metacarpal bone a phalanx, which is flat, long, and 

 tapering from above downwards, superiorly giving off a process 

 which passes upwards for a short distance on the posterior part of 

 the metacarpal bone. 



"The bones o{ the pelvis are so much shortened behind that they 

 throw the centre of gravity in a perpendicular line with the ver- 

 tebrte. The length of the ilia behind the cotyloid cavity is one third 

 of the length of the body in a Gull (Larus); one half in the Loon; 



