260 MARSUPIAL QUADRUPEDS OF NEW HOLLAND. 



phies de Mammalogie' in 1824, completed the natural distri- 

 bution of marsupial quadrupeds, by separating the genera 

 Thylacinus and Phascogale from the Dasyuri, with which M. 

 Geoffroy had associated them. 



As at present constituted, therefore, the marsupial animals, 

 excluding the Monotremata of Geoffroy and Cuvier, are ar- 

 ranged in the following twelve natural genera, thus shortly 

 characterised. 1 



1. Didelphis, Lin. Teeth \p: ft: T^\ tail naked and prehensile; hind feet 



with a clawless opposable thumb. 



2. Cheironectes, 111. Teeth ' F : ft: 1ft \ tail naked and unprehensile ? hind 



feet palmated and with unopposable thumbs ? 



3. Phascogale. Teeth §: ft: ^; the two middle incisors above much long- 



er than the lateral ; the molars armed with sharp tubercles; tail un- 

 prehensile ; toes separate and slender ; the hind thumb tuberculous 

 and without a claw. 



4. Dasyurus, Geoff. Teeth |: ft: §§; tail unprehensile ; feet digitigrade, 



with separate prehensile toes, and a rudimentary tubercle in place 

 of the posterior thumb, in some species. 



5. Thylacinus, Temm. Teeth § : ft : lft\ tail unprehensile ; feet digi- 



tigrade, five toes on the fore and four on the hind. 



6. Perameles, Geoff. Teeth ^ or 'g : ft : "3ft or |§ ; two interior toes next 



the thumb of hind feet united. 



7. Phalangista, 111. Teeth § : g§ : gg ; tail prehensile ; hind thumb op- 



posable, and two next toes united. 



8. Petaurus, Shaw. Teeth | : gg : $; tail unprehensile ; lateral mem- 



branes ; feet like those of Phalangista. 



9. Hypsiprymnus, 111. Teeth § : $: §§ ; hind feet much longer than 



fore, and with the two interior toes united. 



10. Macropus, Shaw. Teeth |: gg: ff ; feet as in Hypsiprymnus. 



11. Phascolarctos, De Blainv. Teeth § : $: f§; the toes before separat- 



ed into two opposable groups, the two interior on one side, and the 

 three exterior on the other ; hind thumb opposable, and two next 

 toes united. 



12. Phascolomys, Geoff. Teeth § : gg : f| ; hind thumb very short, and 



without a claw, next three toes united. 



It will be observed that, from this enumeration of the 

 genera of marsupials, which are here arranged and defined 

 according to the prevailing ideas upon the subject, I have 

 excluded the Halmaturi and some other proposed divisions 

 of M. F. Cuvier, the Isoodon of M. Is. Geoffroy St. Hilaire, 

 and the Acrobata of M. Desmarest, as not being founded 

 upon organic modifications sufficiently influential to entitle 

 them to the rank of generic groups. With these exceptions, 



1 Since the autumn of 1831 , when this paper was written, two new gene- 

 ra of Marsupials have been added to those here enumerated ; Myrmecobius 

 by Mr. Waterhouse, and Chceropus by myself. The former is described in 

 the Transactions, and the latter in the Proceedings, of the Zoological So- 

 ciety.— W. 0. April, 1839. 



