CHAP. IV] THE GENERAL ANATOMY OF THE LEMUROIDEA 79 



" clavicular " component. The M. pectoralis minor is attached 

 partly to the aponeurosis of the M. obliquus extemus abdominis. 

 Yet on the whole, suggestions are afforded to the effect that 

 these shoulder-muscles are less highly developed than in the 

 more purely arboreal Simiidae. 



The M. latissimus dorsi has no scapular area of origin : nor 

 does it blend with the M. teres major. 



The M. dorsi-epitrochlearis arises, not from the tendon of 

 the M. latissimus dorsi, but by two " heads," one from each aspect 

 of the fascial sheath of that muscle. The heads blend to form 

 a muscle traceable below to the olecranon, and thence forwards 

 to the deep fascia over the internal epicondyle and forearm. 



5. The M. biceps brachii is provided with a lacertus fibrosus 

 of remarkable form, for a bundle of muscular fibres leaves the 

 muscular part of the M. biceps to be inserted into the fascia 

 over the M. pronator radii teres. The M. coraco-brachialis is 

 double, part passing dorsally to the tendon of the M. latissimus 

 dorsi to be attached to the humeral shaft in that region. The 

 remaining part represents the muscle as seen in Man save that 

 it extends nearly to the internal epicondyle of the humerus. 

 This muscle appears therefore as a more important element in 

 the arm of the Lemur. 



6. In the forearm, the M. flexor longus pollicis is in the 

 primitive condition of union with the deep flexor muscle of the 

 other digits. Moreover it receives a large contribution from 

 the more superficial part of the M. flexor sublimis digitorum, and 

 thus from the internal epicondyle of the humerus. 



The pollex is furnished with two extensor muscles, viz. for the 

 metacarpal bone (M. abductor longus), and for the terminal phalanx, 

 the M. extensor pollicis brevis being undeveloped. The annular 

 ligaments at the wrist seem to be very strong in comparison with 

 these structures in Man. 



7. The Diaphragm is a thin sheet where it arises from the 

 ribs, and its crura are rather more distinct from the costal portion 

 than in Man. This contrast may well be explained in the light 

 thrown on the relation of the Diaphragm to the habitual attitude 

 and the mode of life of the animal (cf. Dr Wood- Jones, J. A. P., 

 April, 1913). 



