figures of the brains of the Simia Rhesus, Simia Nemestrina, Simia Sabæus, and Cebus Capucinus. If the weight of this latter mass of evidence is not sufficient to make us consider the relations of the parts as seen in our specimen, fig. 2, as mere individual peculiarities, it is at all events sufficient to justify us in denying them, not merely all classificatory, but also all physiological value.
For arrogating importance to any projection or predominance backward of the cerebellum, still less justification exists. For so doing no other colour can be brought forward than such as our own figures can afford, for which we have adduced a sufficient explanation—or such as certain confessedly imperfect figures,[1] taken as they were from a confessedly badly preserved brain, may be thought to furnish, when weighed against the all but unanimous verdict to the contrary, which is obtained by the examination of authentic representations, and of well-preserved specimens. In every specimen, save the single one the subject of this paper, of a simious brain above the grade of a lemur, contained in our Museum, the cerebellum is as much covered posteriorly by the cerebral lobes as we have already shown it to be laterally. The same remarks apply to every one of M. Gratiolet's own figures; the only exceptions to the rule which his plates offer being those which the imperfect figures of Tyson and Sandifort furnish. Tiedemann's Icones of the lower apes are unanimous on the same side, but the figures which he gives of the brains of the orang and chimpanzee, in his work on the Brain of the Negro,[2] represent the cerebellum uncovered, on both sides, to a somewhat greater extent than it is in our figures 3 and 4, on one side[3].
A careful study, however, of our figures, coupled with an examination of the skulls of several anthropoid apes, will lead to the belief that the cerebral hemispheres of the apes bulge less laterally than do those of man; that they are not merely more boat-shaped, and tapering anteriorly and posteriorly, but that they are more wall-sided, and less protuberant laterally.
Though we may be inclined to consider the diminution in lateral expanse, and in backward growth of the posterior lobes, D, of which
- ↑ Schrœder van der Kolk et Vrolik, citt. Gratiolet, Mem. p. 49, Planch vi. 5 and 6.
- ↑ Citt. ap. Wagner's Icones Zootomicæ Taf. viii., figs. 2 and 3.
- ↑ Since the above paragraphs were written, casts have been taken of the interior of the skulls of our second orang and of the chimpanzee with the following results. The cast of the orang's skull approximates more nearly to the proportions of the brain we have figured than does the prepared brain it represents; the relative extent of the space occupied by the mass corresponding to the cerebellum, being somewhat greater than that occupied by the cerebellum itself, in the specimen. Still, in such a view of the cast as that given in fig. 3 of the first of our brains, no cerebellar surface at all comes into view; though a little less cerebral surface comes out laterally than in the preserved brain in a similar view to that in fig. 2. The cast of the chimpanzee's skull represents the cerebral hemispheres as overlapping the cerebellum to a greater extent, posteriorly, than they do in the preparation, the hemispheres having in this, as in certain figured preparations, fallen apart laterally somewhat, and lost thus in antero-posterior, what they have gained in lateral, extent.
