WATERHOUSE AND MILNE-EDWARDS. 95 



indicated by the smooth and anteriorly contracted cerebrum on 

 the one hand, and the convoluted cerebrum, with its rounded 

 anterior portion, on the other. Were I to do so, I should find it 

 necessary to remove some of the Lemurs from their group in the 

 highest order of the first section, and to place them in the 

 second section." 



In the succeeding year, 1844:, M. Milne-Edwards, one of the 

 most distinguished physiologists and zoologists of modern 

 France, proposed, in a highly philosophical paper upon 

 zoological classification in general,* a method of subdividing 

 the Mammalia, essentially similar to that put forward incident- 

 ally by Yon Baer and Eschricht, but lacking, as I conceive, 

 what is the great merit of the latter writers, namely, the clear 

 perception of the classificatory value of the intimate structure of 

 the placenta and the entrance, or not, of a decidual uterine 

 element into its composition. M. Milne-Edwards dwells with 

 great force (as Mr. Waterhouse had previously done) upon the 

 closeness of the general structural affinities which unite the 

 Rodentia, Insectivora, Cheirojrfera, Quadrumana, and Bimana 

 of Cuvier together, and shows that these affinities are denoted 

 by the discoid placenta which they possess in common. 



The diffused placenta (under which head the cotyledonary 

 placenta is included) is stated to be the characteristic of the 

 Ruminantia, Paehi/dermata, Edentata, and Cetacea ; while, 

 lastly, the " Camivora and seals (Amphibies) are distinguished 

 from all the rest by their zonular placenta." 



The singular genus Hyrax, which Cuvier endeavoured to 

 prove to be a true Pachyderm, is considered by M. Milne- 

 Edwards to form one of the series of Mammals with a zonular 

 placenta ; and to represent, in that series, the Pachyderms in the 

 series with diffuse placentation, and the Rodents, in the series 

 with discoid al placentation. 



M. Gervais, in France, and M. Vogt, in Germany, have 

 adopted the placental classification of Milne-Edwards ; while, 

 in 1857, Mr. Waterhouse's proposed, but immediately rejected, 

 cerebral classification was substantially revived by Professor 



* " Annales des Sciences naturelleSi" Seine 3. Tome 1. " Considerations 

 sur quelques Principes relatifa a la Classification naturelle des Animaux." 



