18u'6.] ON THE ANATOMY OF THE CRESTED AGOUTI. 399 



part of the pectoralis major, we are led, as before stated, to regard 

 it as a portion of the last-named muscle. 



The supraspinatus is larger in bulk than the infraspinatus. There 

 is nothing unusual in its attachments. 



The infraspinatus stretches from the infraspinous fossa to the 

 summit of the outer border of the great tuberosity of the humerus. 



The subscapularis is normal, but does not occupy the whole of the 

 subscapular surface of the bone. Its condition approximates very 

 much to that found in Hyrax*. 



The teres major arises from the upper half of the posterior margin 

 of the scapula, and is inserted as usual, but in common with the 

 latissimus dorsi. 



The teres minor has an origin from the inferior third of the poste- 

 rior margin of the scapula ; and its insertion is into the base of the 

 tuberosity of the humerus. It is altogether very small and closely 

 adherent to the infraspinatus. 



Meckel f seems to have failed in detecting this muscle in Rodents, 

 possibly confounding it with the infraspinatus. 



The last-mentioned five scapular muscles present no further dif- 

 ference worthy of mention, either in the Guinea-pig, the Rabbit, or 

 the Hare. 



The biceps has only a single head, and is inserted into the poste- 

 rior border of the ulna by a strong tendon passing deeply between 

 the muscles, and fixed to the ulnar side of the ridge immediately in 

 front of the greater sigmoid cavity (fig. 2, B). 



According to Meckel J this muscle also goes to the ulna in the 

 Porcupine and Beaver ; we have found this also to be the case in 

 the Guinea-pig, Rabbit, and Hare ; there is the usual attachment 

 of the superficial fascia in the forearm ; and in addition a strong 

 fibrous band unites it to the neck and shaft of the radius. 



The coraco-brachialis consists of two parts, the longer of which 

 descends only to about the middle of the shaft of the humerus ; the 

 short part is inserted above the tendon of the teres major§ (fig. 2, C.b.). 



In the Hare, Rabbit, and Guinea-pig this muscle does not descend 

 so far down the shaft of the humerus as in D. cristata, and it is 

 likewise less clearly, if at all, separable into two than in them. 



Meckel || considers it simple and short in the Hare, very long and 

 strong in the Porcupine, and double in the Marmot. 



The brachialis anticus (figs. 2 & 3, B. «.) is peculiar in being 

 divided into two distinct parts, one of which arises at the back of 

 the head of the humerus, much as in Hyrax ^[, curving round the 

 outside of the shaft. Its insertion is by a flattened tendon (much 



* P. Z. S. 1865, p. 338. t Loc. cit. p. 78. 



\ Loc. cit. p. 288. 



§ Since the above was read, Mr. John Wood lias published a paper in the 

 first number of the 'Journal of Anatomy and Physiology.' published at London 

 and Cambridge, 1866. He therein proposes three names for the three portions 

 of the coraco-brachialis. The two parts in the Agouti answer respectively to his 

 coraco-brachialis proprius and coraco-brachialis superior vel brevis {loc. cit. 

 pp. 48 & 41>). 



|| Luc. cit. ]). 280. f P. Z. S. 1865, p. 339. 



