504 MR. ST. G. MIVART ON THE LEMURS. [May 20, 



G. 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 pla- 

 centa is diffuse ! 



The characters above cpioted certainly constitute important di- 

 stinctions ; 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 charac- 

 teristic 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 cal- 

 carine, 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 admitsf 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 affi- 

 nities 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 im- 

 portant 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 con- 

 tinue 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. 



