180 Description of the Plates. 



deltoid; but its orig-in is mainly from the fascia which 

 covers the biceps in front, and being* interposed between 

 that muscle and the tendon of the great pectoral, it is con- 

 tinued up into the tendinous expanse by which the posterior 

 layer of the tendon of the great pectoral connecting- itself 

 more or less intimately with the coracoid head of the biceps 

 obtains an insertion into that bone. The muscle w' is 

 inserted mainly into the inner of the two tendons at its 

 distal extremity. This tendon is prolonged down to be 

 inserted into the radial process of the carpometacarpal bone 

 which carries the pollex. It is more or less intimately 

 connected with the two other long extensor tendons from 

 the muscle w and from the great pectoral, which are here 

 drawn as one ; as also with the short extensor which is not 

 shown in this figure. 



OS. Tendon of great pectoral muscle turned back and seen to 

 be folded upon itself so as to form a pouch with its con- 

 cavity upwards. The posterior portion of this tendon 

 receives at its lower edge the tendon of a cutaneous muscle 

 which is figured as attached to its outer angle, and higher 

 up it receives the main tendon of origin of muscle w , and 

 is ultimately prolonged either separately or in connection 

 with the tendon of the biceps up to the coracoid. 



X. Biceps. Its tendon is seen running upwards to be inserted 

 into the internal anterior process of the upper end of the 

 coracoid; it had a small insertion into the humerus also, 

 which is not shown here. 



y. Portion of inner tuberosity of humerus which overhangs the 

 pneumatic foramen of the bone. 



z. Gizzard. 



For the bibliography of memoirs upon the Anatomy and Physi- 

 ology of Aves, see Selenka in Bronn^s Klassen und Ordnungen 

 des Thier-reichs, Bd. vi. Abtheilung iv. i, pp. 12-13, 1869. 



For the homologies of the Muscles of the Shoulder Joint, see Linn. 

 Soc. Trans., vol. xxvi., p. 609, 1869. 



