136 MARSUPIAL QUADRUPEDS OF NEW HOLLAND. 



abdominal pouch, how it becomes attached to the nipple, or 

 of the nature and circumstances of its subsequent develope- 

 ment. It is not my intention to enter at any length into ana- 

 tomical details, but the following observations are rendered 

 absolutely necessary, as well to preserve the uniformity of my 

 plan, as to put the reader in possession of the principal cir- 

 cumstances regarding the organic structure of these animals, 

 upon which their classification depends. 



The most singular and important of these phenomena is the 

 premature production of the young, which are brought forth 

 in a scarcely organized form, containing, as it were, the mere 

 germ of the future animal, before its senses are fully organized 

 or its members developed, and deposited in the abdominal 

 pouch with which nature has provided the female parent for 

 its reception. In this recess, and in all probability, without 

 the exercise of any act of volition on its own part, the foetus 

 is attached to the nipple of its mother by means of a scarcely 

 formed aperture, which collapses closely round it, and repre- 

 sents the position, as it already executes the functions of the 

 future mouth. Here it continues to cling and imbibe nou- 

 rishment, like a plant engrafted on a strange stem, till the 

 gradual developement of its members, and the more complete 

 organization of its parts, allow it to drop off from the nipple 

 and become an independent being. At this instant, it is pre- 

 cisely on a par, in point of organic developement, with the 

 young of ordinary quadrupeds when first brought forth ; that 

 is to say, though a separate being and possessed of indepen- 

 dent volition, it is, nevertheless incapable of providing for its 

 own wants, but depends, for education aud nourishment, upon 

 the care and assiduity of its parent. Accordingly, it conti- 

 nues, for a considerable time, to occupy the abdominal pouch 

 of its mother, and to be supported by her milk ; occasionally 

 coming out as it acquires size and strength ; and it is only 

 when its increasing growth renders that retreat too small for 

 its reception, that it finally abandons it. 



The next circumstance to be noted in the organization of 

 marsupial quadrupeds, and the last which I consider it ne- 

 cessary to mention for the elucidation of my present purpose, 

 is closely connected with the phenomenon of premature foetal 

 production, and may be considered, in some degree, as a ne- 

 cessary consequence of that singular economy. It consists in 

 the existence of two supernumerary bones, articulated with 

 the pubis, and serving to support the abdominal pouch, and 

 to give attachment to the muscles by which it is expanded 

 and contracted. These bones exist even in the males, which 

 have no abdominal pouches ; and as they are altogether pe- 



