CHAP. IV] THE GENERAL ANATOMY OF GORILLA 



183 



brachialis anticus. It has been recently suggested 1 that in respect 

 of the M. biceps humeri the Simiidae are more highly specialized 

 than the Hominidae; the evidence rests on the reduction observed 

 in the lacertus fibrosus, or fascial expansion of the tendon of inser- 

 tion; the Simiidae seem to have passed through a stage of evolution 

 in which the muscle in question possessed three heads of origin. 



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fwsBfPn^issy 



\r>i 



, 1 1 



Fig. 121. A dissection of the pectoral and axillary regions in an adult Gorilla 

 (Specimen Cy) ; the references are as follows : 



1. M. pectoralis abdominalis (chondro-epitrochlearis). 2. M. pectoralis 



major (cut). 3. M. pectoralis minor. 4. Laryngeal sac extending into the 

 axilla. 5. Tendon of M. latissimus dorsi, with the M. latissimo-condyleus 



extending down the arm. 



6. The tendon of the M. flexor longus pollicis is sometimes 

 absent, sometimes represented by a mere thread arising from the 

 tendon of the deep flexor of the index, or from the anterior carpal 

 ligament. 



The M. extensor minimi digiti is represented by a tendon from 

 the M. extensor communis digitorum. 



The M. extensor indicis resembles its counterpart in Man. As 

 for the extensors of the pollex, it is notewortl^ that a M. extensor 



1 Gronroos, Abh. der Akad. dcr Wist. :u Berlin, 1903. 



