600 Dynamic Theory. 



to the larger sensory and other ganglia rather than to the eerebrum. 

 ( Carpenter.) The brain is relatively larger in small or dwarfish ani- 

 mals than in large ones ; just as it is in the same individual, larger rel- 

 atively in infancy than in maturity. In the Flying Opossum ( Petaurus ), 

 a marsupial, the brain is to the body as 1 to 25. In the large marsu- 



FIGS. 340, 341, 342. Ex- 

 ternal surface of Brain of 



Rabbit ( top fig.). 



Pig ( middle fig.). 



Chimpanzee ( bottom fig.). 

 Ol. Olfactory lobe. 



A. Frontal lobe. 



B. Occipital lobe. 



C. Telnporal * 

 fry. Sylvian fissure. 

 In. island of Reil. 



>V. or. Supraorbital. 

 S/, Mf. If. Super ip 

 and Frontal gyri. 



Superior, Middle 



Ap. Antero-Parietal gyrus. 



Pp. Postero 



K. Sulcus of Rolando. 



PPL Postero parietal lobule. 



OPf. External Perpendicu- 

 lar, or Occipito Temporal 

 Sulcus. 



An. Angular gyrus. 



2, 3, 4. Aimectent gyri. 



At, Aft, Pt. Temporal gyrus. 



SOc,MOc.IO<: Occipital gy- 



Cer. Cerebellum. [rus. 



( Huxley.) 



pial Kangaroo it is as 

 1 to 800. In the Har- 

 vest Mouse it is 1 to 

 20, while in the Capy- 

 bara it is 1 to 300. In 

 the Two-toed Ant-eater 

 it is 1 to 60, while in 

 the Great Ant-eater it 

 is 1 to 500. In the 

 Porpoise four feet long 

 it weighs one pound, 

 but" in the Whale 100 

 FIGS. 340, 341, 342. feet long and 600 times 



heavier, the brain weighs not more than four times as much, or 4 pounds. 

 In the Che vro tain ( Tragulus pygineus ), a pigmy artiodactyle, the brain 

 to the body is as 1 to 80, in the Giraffe as 1 to 800. In the Perisso- 

 dactyle, little Hyrax, it is as 1 to 95, in the Rhinoceros, 1 to 764. In 

 the carnivore Weasel it is as 1 to 90 ; in the Grizzly Bear, 1 to 500. In 

 quadrumana, in the Midas, a Marmoset, it is as 1 to 20 ; in Gorilla, 1 

 to 200. ( Owen.) The large animals appear to lose in weight of brain 

 relatively to the small animals of the same families ; but they gain in 

 its structure. Thus the brain of the Gorilla is possessed of convolu- 

 tions which are absent in the Midas. The brain of the Kangaroo is su- 

 perior to that of the Petaurus, or flying opossum, in convolutions and 

 in the quantity of gray matter in the cortex. 



