258 MARSUPIAL QUADRUPEDS OF NEW HOLLAND. 



world, from the single consideration of the abdominal pouch, 

 and with an utter disregard of all other organic characters, 

 however prominent or influential. Thus were the natural 

 harmony of the genus, and the logical simplicity and preci- 

 sion of its definition, at once destroyed ; nor was it till many 

 years afterwards, that the confusion thus introduced, was fi- 

 nally corrected. Dr. Shaw, the first describer of most of the 

 Australian marsupials, and the principal author of all this 

 perplexity, has, at the same time, the merit of having first led 

 the way towards its subsequent reform, by separating the kan- 

 garoos and flying phalangers from the true didelphes of Lin- 

 naeus, and establishing them, in separate genera, under the 

 denominations of Macropus and Petaurus, by which names 

 they still continue to be designated. This division was pro- 

 posed in the first volume of the c Naturalist's Miscellany,' 

 published in the year 1790, but attracted little notice till M. 

 Geoffroy St. Hilaire effected a more complete arrangement of 

 the marsupials in the 'Magasin Encyclopedique ' for 1796. 

 In that monograph, he restored the genus Didelphis to the 

 original simplicity which Linnaeus himself had contemplated 

 at its formation, by separating from it all the Australian spe- 

 cies which Gmelin and Shaw had incorporated with it ; and, 

 adopting the Macropus of Shaw, arranged the remaining spe- 

 cies in two new genera, by the names of Phalangista and Da- 

 syurus. The following abstract of this distribution, will ex- 

 hibit more clearly the principles upon which it was founded. 



1. Didelphis. Teeth 'g : Jft ^•, tail naked and prehensile ; toesff; hind 



feet with an opposable thumb. 



2. Dasyurus. Teeth § : jj : Ifi; tail hairy and unprehensile ; hind thumb 



short ; other toes separate. 



3. Phalangista. Teeth § : |§ : || ; tail naked and prehensile ; hind thumb 



turned backwards ; index and middle hind toe united. 



4. Macropus. Teeth § : §§ : || ; tail very long, hairy and unprehensile ; no 



hind thumb ; index and middle toe, behind, very small and united, 



It will be observed that, in this arrangement, M. Geoffroy 

 suppresses the genus Petaurus formerly proposed by Shaw, 

 incorporating the animals thus designated with the phalan- 

 gers ; though in so doing he has unwittingly stumbled upon 

 the identical fault which his whole labour was designed to 

 correct ; introducing into his new genus the very confusion 

 complained of in the original distribution of Shaw and Gme- 

 lin, and rendering his definition of the phalangers totally in- 

 applicable to the majority of the species ; for the petaurists 

 differ from the phalangers as well by the unprehensile nature 

 of the tail, as by the possession of lateral membranes. The 

 only natural genus, therefore, which M. Geoffroy definitely 



