1904.] ON BEAINS OF THE POTTO AND SLOW LORIS. 157 



horns, and the glenoid poi-tion of the zygomatic process of the 

 squamosal bone on each side. 



The great vacuity beneath each of the paired horns occui-s in 

 both frontal and parietal bones *, but in the hinder pai't of the 

 skull the cavity becomes smaller, and may be termed the paiietal 

 vacuity, since it occupies the parietal bone only. The internal 

 incomplete pai-titions a,re not symmetrical, and the vacuity as a 

 whole is greatei- in the right side of the skull than in the left. 

 The view shown in text-fig. 10 (p. 156) is obtained by taking a 

 section parallel to the occipital surface of the 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 ai'e the petrous 

 portion of the periotic bone of each side, the tymjoanic cavity, and 

 the part of the squamosal bone that lies behind the zygomatic 

 process. In the distance ai'e seen the foramen magnum and the 

 paramastoid processes. 



4. Note on the Brains of the Potto {Perodicticus potto) and 

 the Slow Loris {^Nycticehus tardigradus), with some 

 Observations upon the Arteries of the Brain in certain 

 Primates. By Frank E. Beddard, M.A., F.R.S., 

 Prosector to the Society. 



[I^eceived January 12, 1904.] 



(Text-figures 11-14.) 



Since my description of the bi'ain of these two species of 

 Lemui'st, the subject has received attention at the hands of 

 Prof. Ziehen t, of Dr. Elliot Smith §, and of others i|. Dr. Elliot 

 Smith has treated of the Lemur brain exhaustively and has 

 fully described both ISfycticehus and Pei^odicticios. As, however 

 so very few brains of both of these Lemurs have been examined by 

 anatomists, I do not think it unnecessaiy 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 fi-ontal 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 Giraft'e 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 pre- 

 served in the Museum of the Royal College of Surgeons, but the whole of the fronto- 

 parietal region has been cut away, so that it now gives no evidence on the suljject. 

 Whether the paired ossicusps of the Giraffe originate in relation to the frontal or to 

 the parietal bones can only be determined by tlie examination of new specinaens of 

 new-l)orn individuals. 



t " On the Bi'ain in the Lemurs," P. Z. S. 1895, p. 142. 



X " Ueber die Grosshirnfurchung der Halbaffen, &c.," Arch. f. Psvchiatrie \-\-viii 

 1896, p. 898. "^ ' ■ ■ 



§ Cat. Phys. Ser. Royal Coll. Surg. vol. ii. (2nd ed.), 1902, and " On the Morpholoo-y 

 of the Brain in the Mammalia, &c.," Trans. Linn. Soc, 2nd ser. Zool. viii. (1903) p. 319. 



1 1 See references below, p. 158. 



