192 ELEMENTS OF OEWITHOLOGY. 



ulna is placed on the external or posterior aspect of the fore- 

 arm, and often shows tubercles which correspond with the points 

 of attachment of the secondary " remiges." It is somewhat 

 longer than the radius, and its proximal end bears posteriorly a 

 more or less enlarged prominence termed the olecranon. The 

 two bones articulate at their distal ends with that part of the 

 skeleton of the pinion which corresponds with our wrist. In 

 the Penguin the bones of the fore-arm are considerably flat- 

 tened. 



The skeleton of the pinion consists of three parts : — (1) the 

 part called " carpus," which corresponds with our wrist-bones ; 

 (2) the part called " metacarpus," which corresponds with the 

 bones in the middle, or fleshy, part of our hand ; and (3) the 

 " phalanges," or bones which correspond with those of our 

 thumb and fingers. 



The carpus in adult birds never consists of more than two 

 bones, which are small, short, more or less rounded or polygonal 

 ossicles. In the very young bird there may be one or two other 

 small bones which with growth anchylose with the bones of the 

 middle hand, i. e. with the " metacarpus." Of the two perma- 

 nently distinct carpal bones one lies at the distal end of the 

 radius, on which account it is often called the radiale, while it is 

 also named the scapholunar bone. The other carpal bone lies at 

 the distal end of the ulna, and is called the vlnare or cuneiform 

 hone. The carpal bones answer to the bones of our wrist. 



The metacarpus is composed, in adult birds, of a singe bone 

 of complex shape and nature. It bears a more or less rounded 

 articular surface at its proximal end, which is somewhat ex- 

 panded ; for the greater part of its extent, however, it consists 

 of a long, stout, cylindrical bone, generally separated by an 

 interspace from a more slender and curved, similarly elongated, 

 bony bar situated externally to the other. This slender external 

 bar answers to that bone of the fleshy part of our hand — or 

 " metacarpal " bone — which supports our middle finger. The 

 stouter bar answers to that bone of the fleshy part of our hand 

 which supports our fore finger or index digit, and it is therefore 

 the "metacarpal of the index." 



On the inner side of the base of this paetacarpal is a small 

 prominence truncated distally. This answers to the bone of the 

 fleshy part of our hand which supports our thumb or pollex, and 

 it is therefore the metacarpal of the pollex. In no existing 

 adult bird are the metacarpals separate. 



