260 



SCIENCE. 



[N. S. Vol. V. No. 111. 



Hapalemur, but with one important excep- 

 tion, namely, the incisors and canines, are 

 normal in form, and not proclivous, as in re- 

 cent Lemurs. This is exactly what we 

 should expect to find in an ancestral Lemur, 

 as that peculiar modernization in the form 

 of the lower incisors and canines in the 

 Lemurs probably occurred at a very late 

 geological epoch. In the jaw oi Megaladapis, 

 of the late Tertiary or Pleistocene epoch of 

 Madagascar, the incisors are not preserved, 

 but, from the extreme massiveness of the 

 jaw symphysis and its upward bend, I 

 think further discovery will show that in 

 this form the lower anterior teeth were up- 

 right in position as in the Eocene Lemurs. 



As already mentioned, the teeth of the 

 Old World Adapidce closely resemble those 

 of the recent Lemuroidea, especially the 

 forms included in the subfamily Lemurmce. 

 The American forms which are supposed 

 to be related to Adapis cannot be con- 

 sidered as ancestral to any of the existing 

 Lemurs, on account of the sexitubercu- 

 lar structure of their superior molars. 

 The question is: Are these American genera 

 monkeys? As before stated, it is very 

 probable that the ancestral Lemur had a 

 generalized type of dentition in that the in- 

 cisors and canines were of the normal form, 

 as in the Apes. The Hyopsodontidce then can 

 hardly be designated as monkeys, simply 

 because they have retained, in the shape of 

 their anterior teeth, the form common to 

 to the ancestors of both monkeys and 

 Lemurs. The term Pseudolemurs, which 

 Schlosser has proposed to apply to fossil 

 Lemurs, with the full number of premo- 

 lars, is appropriate especially for the Ameri- 

 can fossil lemurines. Moreover, this name 

 has the advantage of showing that these 

 forms are not directly ancestral to the true 

 Lemurs, but that they developed parallel 

 with the latter. 



Mivart, in discussing the relations of the 

 Lemurs to the Ungulates, came to the con- 



clusion, that merely on account of the simi- 

 lar structure of the placenta in these two 

 groups, as a result, they cannot be consid- 

 ered as closely related. For we know that 

 in the order Edentata there are several well 

 marked types of placentae, as the zonary of 

 Orycteropus, (2) the diffuse Manis and the 

 discoidal deciduate of the Armadillos and 

 Sloths. Again, as Balfour remarks, " The 

 presence of zonary placentse in Hyrax and 

 Elephas does not necessarily afford any proof 

 of affinity of these types with the Carnivora . ' ' 

 He further states that the resemblance be- 

 tween the metadiscoidal placenta of man 

 and of the Cheiroptera, Insectivora and Ro- 

 dentia is rather physiological than morpho- 

 logical. Balfour considers that, although 

 the placenta is capable of being used to some 

 extent in classification, it does not warrant 

 its being employed except in conjunction 

 with other characters. 



In conclusion, from a study of the oste- 

 ology of the recent and extinct Lemuroidea, 

 I believe that this suborder of the Primates 

 is related genetically to the Apes, that 

 Tarsius is a true synthetic type, connecting 

 the Lemuroids with the Anthropoids, finally 

 Tarsius shows that both Apes and Lemurs 

 have arisen from a common ancestral form. 

 Charles Eable. 



American Museum op Natueal Histoey. 



THE PBI3IAE Y SEGMENTA TION OF THE BRAIN. 



In a recent paper on the ' Segmentation 

 of the N"ervous System of Squalus acanthias, ' 

 Dr. H. V. Neal of Harvard University, 

 entirely sets aside the ' Metameres,' or 

 ' Neural Segments ' observed by Locy in the 

 neural folds, as not having any phylogenetic 

 significance whatever. This conclusion is 

 particularly interesting when it is taken in- 

 to account that Locy claims to have traced 

 these " Neural Segments onward in an un- 

 broken continuity until they become the 

 ' neuromeres ' of other observers. " 



In addition to the above, the chief con- 



