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Show 1904.] OX BRAINS OF THE POTTO AND SLOW LORIS. 157 horns, and the glenoid portion of the zygomatic process of tlxe squamosal bone on each side. The gx-eat vacuity beneath each of tlxe paired horns occurs in both frontal and parietal bones *, but in the hinder part of the skull tlxe cavity becomes smaller, and may be termed the parietal vacuity, since it occupies tlxe pax-ietal bone only. The internal incomplete partitions are not symmetrical, and the vacuity as a whole is greater in tlxe right side of the skull than in tlxe left. The view shown in text-fig. 10 (p. 156) is obtained by taking a section parallel to tlxe occipital surface of tlxe skull, behind the paired horns and just in front of the tympanic orifices : the direction of section is shown by the line 5 in text-fig. 4 (p. 151). The basioccipital bone is cut through, as also are the petrous portion of the periotic bone of each side, the tympanic cavity, and the part of the squamosal bone that lies behind the zygomatic process. In the distance are seen the fox-amen magnum and the paramastoid processes. 4. Note on the Brains of the Potto (Perodicticus potto) and the Slow Loris (Nycticebus tardigradus), with some Observations upon the Arteries of the Brain in certain Primates. By F R A N K E. B E D D A R D , M.A., F.R.S., Prosector to the Society. [Received January 12, 1904.] (Text-figures 11-14.) Since my description of the brain of these two species of Lemurs t, the subject has received attention at the hands of Prof. Ziehen j, of Dr. Elliot Smith §, and of others jj. Dr. Elliot Smith has treated of the Lemur brain exhaustively and has fully described both Nycticebus and Perodicticus. As, however, so vexy few brains of both of these Lemurs have been examined by anatomists, I do not think it unnecessary again to fix the attention * The base of the horn rides equally, so far as can be judged from the specimen under consideration, on the parietal and frontal bones, and a statement to the same effect is made by Owen in his' Anatomy of Vertebrates ' (ii. p. 476, and iii. p. 627). In the young, however, the relations are different; for Owen (Trans. Zool. Soc. iii. 1 [1842], p. 26) describes the separable epiphyses of a very young Giraffe as set upon the frontal bones, while Lankester (Trans. Zool. Soc. xvi. 6, 1902, p. 293) figures a skull, apparently not much older, in which the parietal bone of each side is markedly domed, and supports the horn. The specimen of which Owen made use is still preserved in the Museum of the Royal College of Surgeons, but the whole of the frontoparietal region has been cut away, so that it now gives no evidence on the subject. Whether the paired ossicusps of the Giraffe originate in relation to the frontal or to the parietal bones can only be determined by the examination of new specimens of new-born individuals. f " On the Brain in the Lemurs," P. Z. S. 1895, p. 142. X " Ueber die Grosshirnfurchung der Halbaffen, &e.," Arch. f. Psychiatrie, xxyiii. 1896, p. 898. § Cat. Phys. Ser. Royal Coll. Surg. vol. ii. (2nd ed.), 1902, and " On the Morphology of the Brain in the Mammalia, &c," Trans. Linn. Soc, 2nd ser. Zool. viii. (1903) p. 319. || See references below, p. 158. |
