474 



A/ANUAL OF ELEMENTARY ZOOLOGY 



they present a type of organisation which is on the whole 

 below, rather than above, the average of specialisation in 

 the Mammalia. 



Man is related to a group of lailless, half-erect monkeys which includes 

 __ the gibbons, chimpanzee, gorilla, and orang-utan. From 



these he differs far more strikingly by his mental attri- 

 butes than by his physical features, but the following points are of 

 interest. Man alone walks perfectly upright. His legs are longer than 

 those of the great apes, and the great toe is not opposable. He is less 



Fig. 353. — A dorsal view of the pancreas and duodenum of man, 

 with the pancreatic duct exposed, showing its junction with the 

 bile duct, and the accessory pancreatic duct. — From Cunningham. 



1, Pancreatic duct ; 2, superior (anterior) mesenteric artery ; 3, superior mesenteric 

 vein (branch of portal vein); 4, "head" of pancreas: 5, branch of accessory 

 pancreatic duct ; 6, bileduct ; 7, accessory pancreatic duct or duct of Santorini, 

 communicating both with duodenum and with main pancreatic duct ; S, first 

 (superior) part of duodenum. 



hairy. He has a better command over his voice. His brain is twice 

 the size of that of the gorilla, which in this respect approaches him 

 most nearly, and his cerebral convolutions are more complex than those 

 of the great apes. The cranial part of his skull is correspondingly en- 

 larged. When the face looks forwards the foramen magnum opens down- 

 wards, instead of more or less backwards, as in most other mammals. 



The denial formula is — — '■ — '—*, which is thai of the great apes, but 



2 > 1| 2» 3 

 the small size of the canines and the absence of a gap between them 

 and the incisors ate peculiar to man. The chin and the projection of 

 the nasaljbones to support the nose arc also human features. 



The essential facts of human morphology may be summed up as 



