. A manual of zoology. Zoology. IV. VEErEBRATA : MAMMALIA. 623 and fishes, the cerebeUum (/F)is differentiated into a median vermis and lateral cerebellar hemispheres. In the cerebrum the mantle comes first into consideration. Its frontal lobes grow for- wards over the olfactory lobes, which consecinentlj^ lie farther and farther back on the lower surface. The temporal lobes extend right and left over the optic lobes and down to the floor of tlie cranium; the occipital lobes cover successively the mid brain, cere- bellum, and medulla oblongata. .Since the greatest increase of intelligence lies
. A manual of zoology. Zoology. IV. VEErEBRATA : MAMMALIA. 623 and fishes, the cerebeUum (/F)is differentiated into a median vermis and lateral cerebellar hemispheres. In the cerebrum the mantle comes first into consideration. Its frontal lobes grow for- wards over the olfactory lobes, which consecinentlj^ lie farther and farther back on the lower surface. The temporal lobes extend right and left over the optic lobes and down to the floor of tlie cranium; the occipital lobes cover successively the mid brain, cere- bellum, and medulla oblongata. .Since the greatest increase of intelligence lies within the mammals, the cerebra may be arranged in an ascending series. In the monotremes, marsupials, insectivora, and rodents (tig. (i-tO, A) the olfactor}' lobes arc. Fig. 640.—A, brain of rabbit (after Gegenbaur); B. of fish otter. C, of pavian nionliey 'after Leuret ami Gratiolet). I, cereijruin; III. optic lobes; JF, cerebel- lum; T^ medulla oblony:ata ; ^j, olfactory loljes. visible in front, usually the mid brain behind (///). In the lemurs, carnivores (fig. 040, B), and ungulates the olfactory lobes are completely, the cerebellum jiartly, covered. In man and the anthropoid apes, on removing the roof of the skull, only the two cerebral hemispihores are visible, all other parts being more or less completely covered. Further, it is to be noted that in the first group the surface of the cerebrum is smooth, while in the others the cortex is increased by infolding and the formation of convolutions (gyri and sulci) which reach their greatest complication in the anthropoid apes and especially in man. A conseqitenco of the increase in size of the brain is the great development of the connecting nerve tracts, which become more and more j^rominent as parts of the brain. Thus the two halves of the cerebrum are connected by a large transverse tract, the corpus callosum; two solid cords, the crura cerebri, run back from tlie cerebrum to the other parts, while a transverse commiss
Size: 2268px × 1101px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
