DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 529 



h. Basal Parts and Cerebellum. — A portion of the great marginal convolution appears 

 between the outer and inner olfactory roots. The locus perforatus is narrow ; the cor- 

 pora albicantia full but not unusually prominent. The pituitary body was not removed 

 with the brain ; but I noted its dimension as being moderate. 



The pons Varolii has a somewhat elliptical outline, and seems not particularly elevated ; 

 but the large roots of the 5th nerves may help to mask its real prominence. Otherwise 

 it is thick or deep, and, indeed, within a trifle as large as that in the brain of the Bush- 

 woman so ably described by Mr. Marshall {I. c. p. 523). The medulla oblongata like- 

 wise is proportionally very wide, having a breadth absolutely as great as in the human 

 brain above exemplified. Its pyramidal bodies are well-marked though low. 



Among the distinguishing peculiarities of the cerebellum of Otaria juhata are its 

 great breadth and depth to its length, the fact that it is well nigh overlapped by the 

 cerebral hemispheres behind, and the presence of a deepish excavation below and 

 exterior to the flocculus. The entire organ on its three faces, upper, lower, and pos- 

 terior, presents a semilunar contour. Its lateral hemispheres from behind are abruptly 

 truncate; its base vmequal but most pronounced rearwards; its top lightly arched, 

 shelving sharply downwards and forwards. Hidden as it were under the eave of the 

 cerebral mass, it ordinarily does not appear massive ; yet its proportional, and, in fact, 

 actual size is very considerable. Compared with that of two races of man tabulated 

 and treated of by the above author, it exhibits deficiency in length, surpasses in greatest 

 depth, and is intermediate between that of the European and Bushwoman in breadth. 

 In proportion, therefore, to magnitude of the entire brain, the Otary's cerebellum is 

 exceptionally preponderant in volume. The superior vermiform process is long, narrow, 

 and well-defined; portions of it and the upper posterior lobes are uncovered by the 

 cerebrum, as heretofore mentioned. The tonsil or amygdaloid lobe bears a narrow, com- 

 pressed character. The pneumogastric lobe or flocculus is circumscribed, and, although 

 raised much higher than the last, is not remarkably prominent or free. A most singular 

 appearance of this lower basal aspect of the cerebellum is a large oval depression or 

 hollow, which fits upon the periotic eminence on the posterior fossa of the interior of 

 the cranium. This causes the anterior inferior and partly middle cerebellar lobe to be 

 sunk, while from the flocculus backwards and outwards, with sweeping semilunar turn, 

 a steeply raised bank, including a portion of the middle and post-inferior lobes, abruptly 

 guards the rear of the base of the cerebellum. The said horn-like ridge widens out- 

 wards, or is pyriform ; and from its projecting bulbous contour both exteriorly and pos- 

 teriorly the massive breadth of cerebellum accrues, in spite of the very perpendicular 

 superficies of the hinder face. These peculiarities in shape are simply adaptations to 

 the osseous case, and to the still more remarkable provision made for the great venous 

 blood-channels situated in the region in question. 



i Weight of the Brain. — My memorandum of the weight of the fresh brain and its 

 membranes having been mislaid, I endeavoured to make good in part the omission 



