ON THE ANATOMY OF THE DRILL. 429 



22. On the Anatomy of the Drill (MandrUlus leucoplicms). 

 By Charles F. Sonntag, M.D., F.Z.S., Anatomist to 

 , the Society. 



[Received March 23, 1922 : Read April 25, 1922.] 



(Text-figures 9-24.) 



CONTEKTS. 



Page 



Myology 429 



Alimeutary Canal : 436 



Salivary Glands, Pancreas, Liver 438 



Ductless Glands 439 



Urinogenital Organs 440 



Organs of Circulation 441 



Organs of Respiration 444 



Nervous System 444 



Summarj' and Conclusions 452 



Bibliograplij^ 453 



The literature of the Primates contains very few references to 

 the structure of the Drill, so an account of its anatomy should 

 be useful. The present description is based on the examination 

 of an adult male which died in the Society's Gardens. It had 

 the following proportions : — 



Length from tip of nose to root of tail ... 29-5 inches. 



Tail 3-5 „ 



Length of head 9 ,, 



„ body 20-5 „ 



Arm .... 8 „ 



Forearm 8*6 „ 



Thigh 9-5 „ 



Leg 8-7 „ 



Myology. 



The platysma myoides is strongly developed in both neck and 

 face, and has a well-mai-ked attachment to the lips. The muscles 

 of the lips and frontal region are also very strong and thick ; and 

 it is to their great development that the frequent movements of 

 scalp and exposure of the teeth are due. 



The ternporal and masseter muscles are powerful, and the upper 

 part of the latter is concealed by the parotid gland ftext-fig. 9). 

 But the full, rounded muscle is seen beyond the limits of the 

 gland. The former appears as a well-marked prominence above 

 the zygoma as in many of the Carnivora. 



The arrangement of the vessels and nerves on the surface of 

 these muscles differs from that in many Primates and Cai-nivora, 



Proc. Zool. Soc— 1922, No. XXIX. 29 



