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Show 504 MR. ST. G. MIVART ON THE LEMURS. [May 20, 6. The structure of the extremities-pollex largely developed, and fingers with discoidal terminations. In a private communication the learned Professor has been so kind as to furnish me with further information, the importance of which is not to be contested. He says that the Lemuroids have no decidua, and that the placenta is diffuse! The characters above quoted certainly constitute important distinctions ; nevertheless with respect to some of them a few remarks must be made. First, as regards the brain, Professor Flower, in his paper on the brain of the Javan Loris*, remarks on the presence of the median lobe in Lemur, although it is lost in Hapale, and adds " it is perhaps the sulci of the inner part of the hemisphere that are most characteristic of the Primates, and offer the most striking differential features from the other Mammalia. Here, too, the Lemuridae follow strictly the higher type. That essentially primatial sulcus, the calcarine, which persists deeply marked in the little Hapale jacchus, when every other trace of fissure, except the Sylvian, is gone, is equally well developed in both Lemur and Stenops." M. Paul Gervais himself admits-)- that "les Lemures n'ont jamais que deux circonvolutions autour de la scissure, et, dans certains cas, ils en manquent, tandis que les Carnivores, meme les plus petits, en ont toujours au moins trois." With respect to cranial structure, the prolonged muzzle of Lemur is indeed markedly different from that of most Apes, but hardly, if at all, more so than is that of Cynocephalus chacma from that of Chrysothrix sciurea. The orbit opens more widely into the temporal fossa than in any Ape ; but Tarsius differs in this from Semnopithecus not so very much more than Semnopithecus differs from Mycetes. The development of the pollex is certainly excessive; but the difference in this between any Lemuroid and any Ape is nothing compared with the differences between different Apes. As to that most striking placental character, for the knowledge of which we are indebted to M . Alphonse Milne-Edwards, it must be remembered that the Edentata form a very natural group; and yet the placenta differs strangely in different forms, apparently even to the extent of being non-deciduate, as well as deciduate. Again the Proboscidea have a deciduate placenta, as also has Hyrax, the affinities of which latter to the non-deciduate Ungulata, palaeontology seems more and more to render unquestionable. In spite, however, of all that may be advanced, it cannot be denied that the differences between the Lemuroids and Apes are very important as well as numerous; and great deference is due to the opinion of a naturalist so eminent as Professor Alphonse Milne- Edwards. But to decide the question whether the Primates are still to continue to rank as one ordinal group, or whether the Lemuroids are to be separated as a distinct order, it will be necessary to consider the * Trans. Zool. Soc. vol. v. p. 108. t Loc. cit. p. 27. |