OCR Text |
Show 970 MR. ST. GEORGE MIVART ON THE LEMURIDAE. [Dec. 12, a rudimentary postero-internal cusp. There is also an external cingulum. Perhaps, however, the molars may be better described as consisting each of three cusps (one internal and two external) connected by ridges, and supplemented externally by a cingulum, and internally, except the last one, by an internal cingulum placed behind the internal cusp and resembling a postero-internal one. In the lower jaw the incisors and canines have the form and arrangement common in the Lemuridee. The first lower premolar is very large and caniniform, but with a strongly marked process projecting from its anterior margin. The second and third lower premolars are exceedingly like the second lower premolar of Lndris laniger (see P. Z. S. 1866, p. 157. f. 4). Each has only one external cusp. The first two lower molars consist each of two internal and two external cusps, with a rudiment of a median fifth posterior cusp. The antero-external cusp is considerably larger than, but not so high as, the antero-internal cusp. The postero-internal cusp is much smaller than the external one. The last lower molar is nearly similar to the two teeth in front of it; only the fifth cusp has become very large and distinct. Its tarsal structure is unknown to m e ; but the tarsus appears to be but little elongated. As to the affinities of Lepilemur, it is, I think, impossible to say that it has any marked relationship to any other genus. Perhaps, as M M . Gervais, Schlegel, and Pollen concur in remarking, it rather approximates to Hapalemur than to any other form. The production of the anterior margin of the first lower premolar, as also the form of the two following teeth, recalls to mind (as has been said) the teeth of Indris laniger. The structures exhibited on the one hand by Lepilemur, and on the other by C. furcifer, render necessary some slight changes in the characters before given of the groups to which they are allied. Thus, if the genus Lepilemur is to form part (as I think it must) ot the subfamily Lemurinee, it will be necessary to expunge from the characters of that group the non-inflation of the mastoidal region*, and the characters of Lepilemur, Cheirogaleus, and Microcebus will be as follows : - ' LEPILEMUR*!*. I. % C. g, P-M. 3 M. 3 =^=32. Tail shorter than the body; muzzle longer than the orbit; first upper premolar more vertically extended than the others ; premolars with only one external cusp ; last lower molar with a large fifth cusp ; prcemaxillae very small; an interparietal bone; palate very short; * P. Z. S. 1864, pp. 638 & 639. t Isid. G. St.-Hil. Cat. des Prim. p. 75; Dahlb. Studia Zool. p. 220; Gray, P. Z. S. 1863, p. 144; Wagner, Schreber, Supp. v. p. 147; St. Geo. Mivart, P. Z. S. 1864, pp. 623 & 642; A. Grandidier, Rev. Zool. July 1867, p. 256; Pollen and Schlegel, Rech. sur la Faune de Madagascar, p. 10, pl. 4. |