126 PHYSIOLOGICAL SERIES. 



C. 145. Muscles and nerves of the right fore-limb of a Great 

 Anteater (Myrmecophaga jubata}. The limh is mainly 

 used for diii'ii'infi", and is remarkable for the great size 



Or5 O' c> 



and strength of the extensors of the elbow and of the flexor 

 digitorum. The latter muscle, in particular, is enormous 

 and nearly equals in bulk all the rest of the fore-arm 

 muscles put together. It will be noticed that there is no 

 indication of specially powerful movements of the shoulder 

 such as are found in Echidna (No. 0. 139), and probably a 

 larger share of the work is done by the flexion of the fingers. 

 The following peculiarities should be noted : The extensor 

 antebrachii is assisted in its action by a very powerful 

 dorso-epitrochlearis on the inner side of the arm. The 

 subscapularis is intersected by ten tendinous planes, and is 

 perforated by the short head of the biceps (in the Sloth 

 the subscapularis is completely double.) The biceps is 

 inserted both into the radius and (in conjunction with 

 the brachialis interuus) into the ulna. The epitrochleo- 

 anconeus, as in most other Edentates, is remarkably power- 

 ful. The supinator longus is divided into two parts, one 

 of which has the usual characters, the other is inserted into 

 the fascia covering the flexor surface of the fore-arm. 

 The extensor carpi radialis longus is absent. The flexor 

 carpi ulnaris is double. 0. C. 64 z k c. 



Pouchet, Memoires sur le Grand Fourmilier, 1867, p. 5 ; 

 Windle & Parsons, Proc. Zool. Soc. 1899, p. 314. 



C. 146. The right fore-limb of a Three-toed Sloth (Brady pus 

 tridadylus), showing the muscles. In this Edentate, which 

 spends its life suspended by its hook-like claws from the 

 branches of trees, the extensor muscles are feeblv de- 

 veloped throughout the arm, but the pectoral muscles and 

 flexors are very powerful. The biceps is remarkable. 

 It consists of three parts : (1) A long ribbon-like strip 

 arising from the region of the coracoid in close connection 

 with the deltoid and inserted partly into biceps in. and 

 partly into the fascia on the flexor surface of the fore arm ; 

 it passes superficial to the pectoralis major. (2) The long 

 head arises by tendon from the basa of the coracoid, per- 

 forates the origin of biceps ill., and is inserted into the 



