132 PHYSIOLOGICAL SERIES. 



of large size ; it has a usual but generalized mammalian 



origin from the posterior and outer surfaces of the proximal 



half of the humerus and winds spirally around that bone. 



It joins the tendon of the biceps at its distal end, and is 



inserted with it by a bifurcated tendon upon both ulna and 



radius. 0. 0. 64 z qa. Presented by Prof. McFadyean. 



Ellenberger & Baum, Anatomie des Hundes (Berlin, 



1891), p. 198. 



C. 158. Radius and ulna of a Dog (Canis familiaris), with the 

 rotator muscles. The pronator quadratus is very strongly 

 developed, and occupies nearly the whole of the interosseous 

 space. The upper part is possibly a precursor of the deep 

 portion of the pronator teres. The biceps is attached to 

 both ulna and radius. Presented by Prof. McFadyean. 



Macalister, Jour. Anat. and PhysioL, vol. ii. 1868, p. 8. 



C. 159. Left hand and part of the fore-arm of a Spider Monkey 

 (Ateles sp.). The suppression of the thumb gives rise to a 

 hook-like prehensile hand somewhat similar to that of the 

 Sloth, but far more mobile. The tendon of the extensor 

 metacarpi pollicis is of exceptional strength, and acts upon 

 the hand, as a whole, through the mediation of the thumb- 

 rudiment. The other long extensors of the thumb are 

 absent. The thumb-attachment of the first interosseous 

 muscle is retained. A blue rod is placed beneath the 

 tendon of the extensor ossis metacarpi pollicis, and a 

 green rod between the thumb-rudiment and the index. 

 0. C. 64 M b a. 



Leche, Bronn's Thier-reichs, Bd. vi. (Mammalia), 1897, 

 p. 843. 



C. 160. Left arm of a Baboon (Papio [ Cynocephalus] babuin), 

 showing the chief muscles *. In this ape, which in its 

 locomotion is to a great extent quadrupedal, the muscles in 

 general are powerful and, when compared with those of 



* In dealing with the Old World Apes great assistance has been derived 

 from an unpublished work on Catarrhine Myology, kindly lent by the 

 author, Dr. Arthur Keith. 



