* PECULIAR ORGAiMZATIONS. 145 



are antagonists, which serve in the same manner to shut it ; 

 and this office they perform so exactly, that, in the living 

 animal, the opening can scarcely be discerned, except when 

 the sides are forcibly drawn asunder.* Is there any action 

 in this part of the animal, any process arising from that 

 action, by which these members could be formed? Any 

 account to be given of the formation, except design ?t 



* Goldsmith's Nat Hist. vol. iv. p. 244. 



t There is a very considerable number of animals possessed of the 

 same structure which is here described as existing in the opossum, to 

 which the attention of naturalists has been more particularly called 

 since the first publication of this work. The animals of this kind are 

 called marsupial, from the pouch or marsiipium which distinguishes 

 them. This prevision also has a relation to circumstances in the re- 

 production of these animals to which Dr. Paley has not referred. He 

 appears merely to regard it as a place of refuge and deposit for the 

 young ; somewhat in the same way as the wings of a hen arc for its 

 brood. The fact is that the young of these animals are born prema- 

 turely, and in a very imperfect and unformed state ; and the pouch of 

 tlie parent seems properly intended for a residence during the com- 

 pletion of the piocess of development. The Kangaroo is an instance 

 of this kind. When full grown it is six feet in extreme length, and 

 weighs an hundred and fifty pounds. When born it is only one inch 

 in length, and w^eighs but twenty grains. The fore legs are scarcely 

 ■distinguishable, and the hind ones, which in the adult state form half 

 the length of the body are marked only by slight projections at the 

 parts where they are afterwards to grow. In lact the Kangaroo at 

 birth is as imperfectly formed as the young of any other animal would 

 be when but a quarter part of the proper period of its growth within 

 its parent had elapsed. 



It is remarkable that it has never yet been ascertained whether 

 these little embryos are conveyed by the parent animal, or whether 

 they find their own way, into the pouch. Having scarce the exercise 

 •of any of the senses, and being without umbs,it seems almost impossi- 

 ble they should make their way there by their own exertions. How- 

 ever this may be, they are found in the pouch closely attached, and 

 as it were glued to the nipples, by the mouth or rather by that aper- 

 ture which afterwards becomes a mouth. Here they remain, never, 

 quitting their hold, until a sufficient period has elapsed for their growth 

 to be completed, and they have thus arrived in regard to form and struc- 

 ture upon an equality with other animals at the usual period of birth. 

 When this is accomplished, tliey undergo, as it were, a second birth, 

 and emerge from the pouch : but return occasionally for the purpose 

 of feeding, and for that of protection from danger. 



No marsupial animal was known before the discovery of America, 

 of which the opossum is a native ; and this animal was at first almost 

 regarded as a sort of exception to the laws of nature; since the discov- 

 ery of New Holland, however, and the investigation of its Natural 

 History, it has been found that the marsupial animals, so far from 

 forming an exception to the general construction of animals on that 

 continent, constitute the prevailing model. With a very few excep- 

 tions, all the native animals of New Holland are of the marsupial tribe. 



Ed. 



