12 PEOFESSOE OWEN ON THE CHAEACTEES, ETC. 



the rest of the world, " some," he writes, " corresponding with the 

 Carnaria, some with the Hodentia, and others again with the 

 Edentata*.'''' 



M. Isidore Geoffroy St. Hilaire, in his ' Classification paralle- 

 lique des Mammiferes,' published in 1845, raises the Marsupialia 

 to the rank of a distinct class, and literally exemplifies the idea of 

 Cuvier by placing its subdivisions, as orders, in parallel equivalents 

 with the orders of the Placentalia. 



It does not appear, however, that Cuvier meant to do more 

 than indicate certain relations of analogy ; just as the relation of 

 the pedimanous and frugivorous Marsupials to the pedimanous 

 Quadrumana of S. America, that of the marsupial Hyaena (Tliyla- 

 cimis) to the Wolf, of the Flying Petaurist to the Flying Squirrel, 

 of the Wombat to the Beaver, of the Kangaroo to the Ruminant, 

 of the Koala to the phytiphagous Sunbear, of the Opossums to 

 the Shrews, and of the Echidna to the Anteater, &c, had been 

 pointed out by myself. My esteemed friend and colleague Mr. 

 Waterhouse, whilst admitting the justness of some of these com- 

 parisons, appended a timely warning, in a valuable note in his 

 comprehensive and excellent history of the Marsupialia-f, against 

 the mistake to which the young zoologist might be liable, of con- 

 cluding the analogical groups of the Marsupialia and Placentalia 

 thus indicated to be of equal rank and value. I have always par- 

 ticipated in this conviction of the lower value of the Implacentalia 

 as compared with the Placentalia ; and have used those terms 

 merely as useful collective or general signs of certain modifica- 

 tions of structure, which are associated with the development and 

 non-development of the placenta. 



In like manner, when indicating the highest generalization to 

 which I had arrived after comparisons of the dentition of the 

 Mammalia, by the terms ' monophyodont ' and ' diphyodont J,' 

 signifying respectively the single and double set of teeth deve- 

 loped in different groups of the class, I have been careful to guard 

 myself from being misunderstood, as supposing that the monophyo- 



* Regne Animal, ed. 1829, vol. i. p. 174. 



t Natural History of the Mammalia, 8vo. 1815, part i. p. 14. I must 

 remark, however, that in stating " by Prof. Owen and some other naturalists, 

 the present section (Marsitpiata) is ranked as a subclass," the reader, from the 

 peculiarly extended signification given to the term ' Marsupiata,' might be mis- 

 led. The Marsupialia form one of the orders of my subclass Implacentalia. 

 See the articles 'Marsupialia' and ' Monotremata,' in the " Cyclopaedia of Ana- 

 tomy," vol. hi. 1841. 



X Cyclopedia of Anatomy, part xxxtH. 1849. Pliil. Trans. 1850, p. 493. 



