124 PHYSIOLOGICAL SERIES. 



the muscles are \vell developed, those brought into play 

 during the backward scratching movements (latissimus 

 dorsi, extensor antebrachii, flexor digitorum) are exception- 

 ally powerful. Apart from the intrinsic strength of these 

 muscles, the efficiency of the latissimus dorsi is largely 

 increased by its direct insertion upon the internal condyle 

 of the humerus. The large size of the pronator teres, in 

 comparison with the supinators, may perhaps be accounted 

 for by another digging movement, i. e. the turning out- 

 wards of the palm of the hand to throw the dirt clear of 

 the body. Besides these features connected specially with 

 the action of the limb, the following muscles are of great 

 interest owing to their strongly reptilian characters : The 

 supracoracoideus (found among mammals only in the 

 Monotremes) . The biceps with no scapular origin. The 

 coraco-brachialis longus and brevis, two large muscles with 

 striking reptilian features (No. C. 130). The extensor 

 carpi radialis longior inserted upon the scapho-lunar (the 

 usual reptilian insertion). Attention is also drawn to the 

 following peculiarities : The latissimus dorsi is double, one 

 head originating from the dorsal vertebrae (cut short in the 

 specimen), the other from the posterior angle of the sca- 

 pula. Owing to the outward rotation of the anterior border 

 of the scapula, the origin of the supraspinatus has been 

 shifted to its ventral surface and that of the subscapularis 

 to the dorsal. There is a distinct epicoraco-brachialis. 

 The flexor digitorum (probably answering to both flexor 

 sublimis and profundus) forms a single fleshy mass from 

 which at the wrist five stout tendons are given off to the 

 fingers. The palmaris longus is absent. 0. C. 64 z. 



C. 140. The deep muscles of the left fore-limb of a Spiny Ant- 

 eater ( Tachyglossus [Echidna] aculeata). 0. C. 64 z a. 

 Westling, Bihang Svenska Vet.-Akad. Handlingar, 

 Stockholm, Bd. xv. 1889, p. 12. 



C. 141. The right fore-limb of a Duck-billed Platypus (Ornitho- 

 rhynchus analinus), showing more especially the muscles 

 of the fore-arm and hand. In the main they agree with 

 those of Echidna. The insertion of the pronator teres is, 

 however, to the middle of the radius, and there is a distinct 



