20 ANDREW JACKSON HOWE. 



ated upon the organization of these creatures, a pre- 

 hensile tail being obtained at the expense of thumbs. 

 The brain constitutes such a distinctive feature 

 of man's superiority over the inferior animals, that 

 though other parts of lower organizations were equal 

 to corresponding parts in man, and even excelled them, 

 man as a psychological being would still stand unap- 

 proached. Some of the Gibbons and most of the 

 cebidce possess an arrangement of the encephalic mass 

 which quite closely resembles the general contour of 

 the human brain. If the " facial angle " of Camper 

 signified what has been claimed for it as a measure of 

 mental capacity, the tiny Marmoset of South America 

 would rank higher as an intellectual being than man, 

 for the angle is greater in its face and head, though its 

 brain contains little gray matter and no convolutions. 

 The Siamang has retracted jaws, incisor teeth which 

 meet each other vertically, a prominent, forehead that 

 gives the face a human appearance, yet its cerebrum 

 does not overlap the cerebellum as completely as does 

 that of the Marmoset. The Ateles has a projecting 

 muzzle, therefore its face is not so human in appear- 

 ance as is that of the Siamang, but its forehead is 

 more projecting, and the occipital lobes which possess 

 cornua and lesser hippocampi, quite cover and conceal 

 the cerebellum, as do corresponding parts in the 

 larger apes and man. The spider-monkey also pos- 

 sesses folds of brain substance interposed between the 

 parietal and occipital lobes, which in man are called 

 " bridging convolutions." In this feature the Ateles 

 surpasses the largest apes. But while so many cere- 

 bral characters of a high anthropoid nature are pos- 

 sessed by the spider-monkey, it must be borne in 

 mind that the brain of the animal will not weigh 



