14 MR. F. E. BEDDARD ON THE [Jan. 6, 



(8) In addition to the biceps there was a very remarkable muscle 

 present which I have once before observed ; unfortunately I have no 

 note of the bird in which it occurred. This muscle is a kind of 

 accessory biceps : it arises from the humerus just below the insertion 

 of the deltoid by a tendinous sheet ; in the specimen before me, as 

 shown in the drawing (fig. 2, Bi.2, p. 13), the muscle was pro- 

 longed forwards, running parallel to the fibres of the deltoid and 

 closely embracing the nerve {N.) which supplies this part of the 

 wing ; the appearances presented were suggestive of an origin from 

 the sheath of the nerve, which of course seems hardly likely. The 

 muscle gradually diminishes in width as it passes down towards the 

 radius and becomes tendinous, but I did not succeed in making out 

 the exact mode of its insertion. 



Dr. Gadow mentions no muscle that can be compared with this. 



(9) The Expansor secundariorum is present ; the tendon is of 

 considerable size ; I did not observe its mode of insertion. The 

 Expansor secundariorum seems to be present in all the Cranes and 

 Plovers and in most Herodiones ; its absence, however, in Oancroma 

 and Egretta shows that it is on the wane in that group. 



(10) The Triceps has the usual two heads situated close together 

 just beneath the head of the humerus. 



(11) The Pectoralis primus has a large insertion area on the 

 crista superior of the humerus ; there is no second insertion such as 

 is met with among many birds. 



(12) The Pectoralis secundus is well developed, and its origin 

 extends back to nearly the end of the narrow sternum. 



(13) The Goraco-brachialis longus arises from the coracoid near 

 to its articulation with the sternum and also from the sternum 

 itself. 



At present there does not exist material for a detailed comparison 

 of the musculature of the forearm and hand in different groups. 

 The work of Dr. Gadow [16] upon Bird Anatomy contains a good 

 general account of these muscles with their variations in a few types, 

 while Dr. Shufeldt's essay on the Raven [20] and some few papers by 

 other writers deal with these muscles in special forms. Although 

 the object of the present paper is principally systematic, I give 

 an account of the principal muscles of the forearm, since Rhino- 

 chetus is probably not an accessible type to many of those who are 

 engaged in the study of the muscular anatomy of birds. I have 

 not studied the intrinsic muscles of the hand in my specimen, in the 

 hope that on some future occasion I may have the opportunity of 

 dissecting a recently dead specimen. 



"When the skin is cut off from the outer side of the forearm, most 

 of the extensor muscles are revealed without further dissection. 



(1) Extensor metacarpi radialis longior. — This muscle consists 

 of two distinct parts with separate origins but a common insertion : 

 the outer part arises by a thin tendon ; this soon expands into a 

 fusiform muscle which is decidedly smaller than the second part of 

 the extensor ; the muscle passes into a tendon at a point about half- 



