| OCR Text |
Show 158 MR. F. E. HEDDARD OX BRAIXS [Jail. 19, of students of tlxe brain upon these Lemurs, since I have two new brains of Nycticebus and one of Perodicticus to report upon, none of which has been studied by any other person. Of Nycticebus tardigradus eight brains * altogether have been examined, one by Sir William Flower f, one by myself J, four by Ziehen §, one by Chudziaski ||, and one by Flatau and Jacobsohn^f. The measurements of tlxe cex-ebx-al hemispheres of m y two new brains are as follows:- A. Length 30 mm., greatest diameter 26 mm., height 20 mm. B. „ 26 mm., „ „ 26 mm., „ 19 mm. I could detect no trace whatsoever of a distinction between an upper supra-Sylvian sulcus and a lower pseudo-Sylvian sulcus such as Dr. Elliot Smith descxibes axxd figures; nor could I see the little forwardly projecting end of the Sylvian which he figux-es in the lateral view of tlxe brain. I observed in m y brain A (the lax-ger of the two) that at the point where the Sylvian sulcus becomes continuous with tlxe lateral sulcus, the latter has a minute forwardly directed continuation, which may be considered to represent the anterior half of this fissure in Perodicticus; and I may call attention to the intex-esting fact that Dr. Elliot Smith has himself figured in the Potto ** a feeble union between tlxe Sylvian and the latex-al fissures. Tlxe lateral fissure exhibits a slight difference in direction in the two brains which I have studied. In the smaller one the two fissures are distinctly more parallel to each other and thex-efore to tlxe iixtex-hemispheral sulcus. In regard to the relations between the lateral sulcus and tlxe post-lateral (= my " pax-ieto-occipital") Dr. Elliot Smith writes :- "It is intex-esting to note in these two casts [of the brain-cavity of Nycticebus] that thex-e is a definite post-lateral sulcus in all four hemispheres, and in none of them is tlxe caudal extremity of the lateral sulcus bent inward, as is invariably the case when the separate post-lateral sulcus is absent. A comparison of the brain-case of my type specimen with tlxe othex- cranium from Ghizeh shows that the separate post-lateral sulcus occupies the same position in regard to the skull as the niesially bent end of the lateral sulcus of the other specimen "ft. In the two brains examined by myself and reported upon hex-e, tlxe caudal extremity of the lateral sulcus is bent inwards (more in one brain than in the othex-) and the post-lateral sulcus is well developed. In both brains the sulci are developed on both sides, and they just dip over the inter-hemispheral margin lying thex-e midway between the two parts of the calcax-ine fissux-e. The fissure which Dr. Elliot Smith letters "f" is bracket-shaped in the smaller of m y two brains, which appears * One of these has been described both by Ziehen and by Elliot Smith. f " On the Brain of the Javan Loris," Tr. Z. S. vol. v. p. 103. X TMC cit. p. 144. § Loc. cit. p. 902. || Bull. Soc. d'Anthr. 1895, p. 436. % Handbuch d. Anatomie .... d. Centralnervensystcnis d. Samrethiere, Berlin 1899. ' ** Cat. Phys. Ser. Royal Coll. Surg. p. 378, tig. 220. ff Trans. Linn. Soc. loc. cit. p. 343. |
