180 



THE GENERAL ANATOMY OF GORILLA 



[SECT. A 



The remainder of this account will be subdivided into sections 

 in the same way as in the other animals described. 



1. Of the cutaneous muscles, M. platysma is notable for its 

 extraordinary coarseness (cf. Fig. 120). Differentiation of the 

 muscles of expression has reached a stage not far removed from 

 that obtaining in Man. The dorso-humeral muscle has disappeared, 

 save in anomalous instances where it appears as an " Achsel-bogen" 

 or axillary band. 



Fig. 120. Facial musculature of an adult Gorilla. Note the great development 

 of the anterior fibres of the platysma. The specimen forms part of the Holt 

 donation to the Cambridge Collection. (Specimen Cy.) 



2. In an adult male Gorilla, I found the M. digastricus to 

 consist of the normal anterior and posterior parts. The tendon is 

 long and stout so that it is clearly traceable through the M. sterno- 

 hyoideus. The anterior belly is a wide sheet arising partly from 

 the hyoid bone. It quickly approaches its fellow of the opposite 

 side, the triangular gap between the two being largely composed 

 of fibrous tissue. Near the symphysis, the deeper fibres are 

 attached to the margin of the mandible, the attachment being 

 simply linear, but continuous from side to side of the middle line. 

 The more superficial fibres spread out into a connective tissue 



