340 ON THE MARSUPIAL QUADRUPEDS 



These reflections are naturally suggested by an inquiry 

 into the principles which determine the natural arrangement 

 of marsupial quadrupeds ; a group of mammals, in which, as 

 I have endeavoured to show, the distribution into families is 

 more arbitrary, and less consistent either with the organic 

 structure of the animals, or with the habits and economy of 

 their lives, than in any other group of equal value or extent. 

 I proceed to point out the really influential modifications up- 

 on which these functions depend, and which alone should be 

 taken into account in the zoological arrangement of these 

 animals. And first with regard to their dental system. 



Two principal forms of dentition prevail among the marsu- 

 pials ; which, from the genera in which they may be consi- 

 dered as characteristically presented, I shall take the liberty 

 of calling the didelphoid and macropoid forms. The first is 

 characterised by eight or ten incisors in the upper jaw, and 

 six or eight in the lower ; distinct, well-developed canines, of 

 the normal form ; and six, or more commonly seven, molars 

 on either side, both above and below ; of which two or three 

 are false, and the remaining four real molars, provided with 

 sharp tubercles, and adapted to an insectivorous regimen. — 

 The incisors, which exceed in number those of all other mam- 

 mals, are small, simple, upright and arranged regularly in a 

 portion of a small ellipse, the two middle above being gene- 

 rally a little longer than the lateral, and partially separated 

 from one another ; the canines, as in all marsupial quadru- 

 peds, are situated in immediate contact with the intermaxil- 

 lary suture, and are, generally speaking, of tolerable size ; 

 but the tubercles on the posterior molars are by no means so 

 sharp and pointed as in the true Insect ivor a ; and, except 

 among the smaller species, there is good reason to believe 

 that insects form but a very small portion of the natural 

 food of the animals. The Opossums, for instance, notoriously 

 live upon wild fruits, and it is only when these fail in the 

 woods, that they betake themselves to an animal diet; the 

 Thylacines and Dasyures are purely carnivorous ; and the 

 testimony of all colonial authorities, as well historians and 

 travellers, as officers and other gentlemen with whom I have 

 conversed on the subject, agrees in representing the Perame- 

 les, or, as they are called by the settlers, Bandicoots, as equal- 

 ly destructive to their potato and com crops, scratching up 

 and devouring the tubers of the former, as well as all other 

 kinds of bulbous roots, whether wild or cultivated ; and gree- 

 dily devouring the tender and milky grains of the young maize. 

 That they occasionally, perhaps in some situations habitually, 

 feed upon insects, I have no doubt, as I am well aware that 



