TEE CEREBRUM. 



801 



suddenly and greatly flattened on each side ; it is nearly smooth, and is joined, 

 behind and downwards, to the second frontal convohition and external root of 

 the olfactory lobe ; it is confounded, above, with the convohition surrounding^ 

 the crucial fissure. The upper face of the parieto-occipital lube forms a loniz-er 

 trianirle than in Solipeds and Ruminants. 



"YhQ first parieto-occipifal roiwolution, double as in the other animals, bifurcates 

 in front ; its internal branch nins into the extremity of the second convolution 

 and the sigmoid f/f/rus, while its exlernal branch, as in the Ox, passes on to the 

 ascending frontal convolution. If we supposed this branch interrupted by a 

 notch, the fissure of Rolando would be disposed, in front, in the same way as iu 

 Solipeds. 



Cat. — The brain of the Cat is more regularly ovoid, and more flattened than 



Fig. 446. 



Fig. 447. 



BRAIN OF THE DOG (UPPER FACE). 

 NATURAL SIZE. 



B, Medulla oblongata. C, Cerebellum: 1, 

 middle lobe of ditto ; 2, 3, lateral lobes of 

 ditto, s, Inter- hemisphei'ical fissure; 4,4', 

 crucial fissure ; 5, sigmoid gyrus ; 6, second 

 parietal convolution; 7, first parietal con- 

 volution; 8, limiting frontal convolution; 

 9, first and second frontal convolutions. 



BRAIN OF THE CAT (NATURAL SIZE). 



B, Medulla oblongata. c, Cerebellum : 1, 

 . middle lobe of ditto; 2, ,3, lateral lobes of 

 ditto. S, Inter-hemispherical fissure ; 4, 4, 

 crucial fissure; 5, second parietal convolu- 

 tion; 6, first parietal convolution; 7, limiting 

 frontal convolution ; 8, sigmoid gyrus. 



that of the Dog. The convolutions, less flexuous than in that animal, also aflfect 

 the longitudinal type, as may be seen in Fig. 447. The crucial fissure is placed 

 quite in front, near the anterior extremity of the hemispheres, which is occupied 

 by a very short, first frontal convolution. The occipital portion of the parieto- 

 occipital lobe is very reduced, and the region it occupies is indented to receive a 

 part of the cerebellum. 



Comparison of the Cerebrum op Man with that of Animals. 



The cerebrum of Man (Fig. 448) is distinguislied by its regularly ovoid shape, and its great 

 development, particularly behind, where it covers the cerebellum — a feature never observed 

 in animals. 



