. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Fig. 116. ,--fs. —3, Bi'di/i uf Macroptts mnjur. cerned, the brains of the herbivorous Marsu- pials are more complicated than those of any of the Rodent Mammalia. The cerebellum presents the usual close-set, sub-parallel, trans- verse convolutions: it is remarkable for the large proportional size of the median or vermi- form lobe, as compared with the lateral lobes, especially in the carnivorous and insectivorous Marsupials, where this condition is associated with a corresponding diminution of their com- missural band or
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Fig. 116. ,--fs. —3, Bi'di/i uf Macroptts mnjur. cerned, the brains of the herbivorous Marsu- pials are more complicated than those of any of the Rodent Mammalia. The cerebellum presents the usual close-set, sub-parallel, trans- verse convolutions: it is remarkable for the large proportional size of the median or vermi- form lobe, as compared with the lateral lobes, especially in the carnivorous and insectivorous Marsupials, where this condition is associated with a corresponding diminution of their com- missural band or ' pons Varolii,' as is shown in the view of the base of the brain of an Opos- sum (fig. 116, 4). In the Kangaroos, Perameles, Phalangers, and Koala the hemis- pheres or lateral lobes of the cerebellum are characterized by asmall subspherical lateral process or appendage (<•» ./&• 115), which is lodged in a peculiar fossa of the petrous bone above the internal meatus : there are cor- responding but less produced processes in the Dasyures and ,qjm,_ Opossums, but they Brain of Didelphys Vir- are not developed in giniana. the Wombat. On the upper surface of the cerebellum the medullary substance appears superficially at a small tract between the ver- miform processes, marked with an asterisk in figures 115 and 117. The simple disposi- tion of the arbor vitae is shown in Jig. 118, /. Behind the pons Varolii are seen the two trapezoid bodies (c, Jig. 116); and the corpora pyramidalia (c/) are always clearly distin- guishable from the corpora olivaria. The cruru cerebri, which, in the Opossum (c,fig. \ 16) are left exposed below, like the optic lobes above, by reason of the small proportional size of the cerebrum, are more completely concealed in the brain of the Kangaroo and Wombat. The nati- form protuberances form a great proportion of the under part of the cerebral hemispheres in all the Marsupials; their external boundary, which is basial in the Wombat and Kangar
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