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Show 962 MR. ST. GEORGE MIVART ON THE LEMURID.E. [DeC. 12, it true that there is in C. milii, as De Blainville remarks*, a certain elongation of the astragalus as compared with the other tarsal bones, but the naviculare is quite short comparatively, instead of being much elongated as it is in M. pusillus. Indeed, in the latter species, the naviculare is absolutely as well as relatively longer, although in it (i. e. in M. pusillus) the length of the dorsal and lumbar regions together is only 2*75 inches, while the same part in C. milii is 5 inches in length. „ .,.. .. .„ ° • C. milii. M. pusillus. inch. inch. Length of cuboid *21 *16 • of os calcis *52 *36 of dorsum of naviculare .... *17 '20 of astragalus '35 *20 The dimensions of the tarsal bones of M. myoxinus are almost the same as those of M. pusillusf. In addition to this distinction in the tarsus, the palate has no defects of ossification in C. milii; the fifth cusp of the hindmost lower molar is rudimentary, instead of being distinct; there is a small malar foramen, while in M. pusillus there is none. The carotid foramina on the basis cranii are also very conspicuous, instead of being almost hidden by the auditory bullae; the pterygoid fossae are also larger; and, lastly, the first upper premolar is slightly caniniform and considerably longer than the second one, instead of being smaller and slightly shorter than the second one as in M. pusillus. On the other hand, C. milii agrees with M. pusillus in having the palate prolonged, the posterior palatine foramina large, a distinct interparietal bone, in the absence of any enlargement of the mastoidal region of the periotic, and in the other characters before assigned to Microcebus^. In both skeletons there are thirteen dorsal and seven lumbar vertebrae ; but neither the axial nor the appendicular skeletons present any noteworthy characters in either specimen. The close affinity of the M. myoxinus of Peters § to M. pusillus being as unquestionable as is their specific distinctness, it is desirable to know if it presents any characters tending to bridge over the gap separating the last-named species from C. milii. Now M. myoxinus differs from M. pusillus, besides external characters (as has been pointed out by Dr. Peters ||), in its shorter and less-pointed muzzle, in the greater production forwards of the praemaxillae, the larger size of the openings in the palate, and also, possibly, in the somewhat longer symphysis of the mandible. Moreover the contour of the anterior nares, viewed in profile, is less concave, and the palate is less prolonged backwards. Again, the first premolar is quite as extended, vertically, as is the second, instead of * Osteographie, Lemur, p. 12. t Professor Peters has been kind enough to send m e the exact length of the tarsal bones of his M. myoxinus. % P. Z. S. 1864, p. 640. § Reise nach Mossambique. p. 14. || Ibid. p. l'J. |
