WINGS OF BIRDS. 13 



In looking at the drawings of Commerson, as published by Geoffroy, and 

 in reading his account of the Ch: Milii, we cannot but be struck with the close 

 affinity between these animals and those of the genus Microcebus. Indeed we 

 cannot help suspecting, that the latter species belongs to this genus; for, be it 

 observed that Commerson gives his three species of Cheirogaleus as having the 

 nails on the fingers both of the anterior and posterior hands elongated and 

 claw-like. — It is true, that Geoffroy says, that in this point Commerson has 

 committed an error; but surely if we are to trust to one part of his draw- 

 ing, we are to place confidence in the whole ; and it is only because the nails 

 are not found to be so constructed in the Ch : Milii, that he regards Com- 

 merson as wrong. — We have not, indeed, had an opportunity of seeing the 

 specimen on which Geoffroy has founded his latter species ; but we have care- 

 fully examined (and one anatomically) two species of the genus Microcebus, 

 respecting which we feel on safer grounds than with regard to Cheirogaleus. — 

 To this genus we propose to turn our attention in the next number of the 

 Naturalist. 



DESCRIPTION OF THE MUSCULAR APPARATUS OF THE WINGS 



OF BIRDS. 



By William MacGillivray, A. M., F. R. S. E., M. W. S., &c, 



Conservator of the Royal College of Surgeons in Edinburgh. 



The frame work of the wing is composed of a series of bones attached by a 

 loose joint to the solid apparatus of the scapula and clavicles, and folding up by 

 hinges into three pieces, the humerus or brackiam, the cubitus, and the hand, 

 so as, when not in use, to be conveniently disposed of by the side of the body. 

 The first bone, the os humeri, brachial bone, or bone of the arm, is articulated 

 by a rounded surface to a corresponding cavity formed between the coracoid bone, 

 or posterior clavicle, and the scapula, in such a manner as to allow great free- 

 dom of motion. When at rest, this bone is directed backwards, more or less 

 parallel to the spine. Its distal extremity forms, with the proximal extremity of 

 the cubital bones, the ulna and radius, an oblique hinge-like joint, which allows the 

 cubitus to be folded up parallel to the brachium, and nearly in the same plane. 

 The third portion, the hand, on the contrary, is jointed so as to fold under the 

 cubitus in a perpendicular plane. These solid parts are moved upon each other, 

 and upon the scapula, by a complicated muscular apparatus ; and the arm, thus 



