MARSUPIALIA. 83 



their young, whose state of development at birth is extremely small. 

 Incapable of motion, and hardly exhibiting the germs of limbs and 

 other external organs, these diminutive beings attach themselves to 

 the mammce of the mother, and remain fixed there until they have ac- 

 quired a degree of development similar to that in which other animals 

 are born. The skin of the abdomen is almost always so arranged 

 about the mammae as to form a pouch in which these imperfect little 

 animals are preserved as in a second uterus; and to which, long 

 after they can walk, they always fly for shelter at the approach of 

 danger. Two particular bones attached to the pubis, and inter- 

 posed between the muscles of the abdomen, support the pouch. 

 These bones are also found in the male, and even in those species 

 in which the fold that forms the pouch is scarcely visible. 



Another peculiarity of the Marsupialia is, that notwithstanding a 

 general resemblance of the species to each other, so striking, that for 

 a long time they were considered as one genus, they differ so much 

 in the teeth, the organs of digestion and the feet, that if we rigor- 

 ously adhered to these characters, we should be compelled to sepa- 

 rate them into several orders. They carry us by insensible grada- 

 tions from the Carnaria to the Rodentia, and there are even some 

 animals which have the pelvis furnished with similar bones; but 

 which, from the want of incisors or of all kinds of teeth, have been 

 approximated to the Edentata, where, in fact, we shall leave them, 

 under the name of Monotremata. 



The first subdivision of the Marsupialia is marked by long canini, 

 and small incisors in both jaws, back molars bristled with points, 

 and all the characters in general of the insectivorous Carnaria; the 

 animals that compose it are also perfectly saiilar to the latter in 

 their regimen. 



DiDELPHis, Lin. 

 The Opossums, which of all the Marsupialia have been the longest known, 

 form a genus peculiar to America. They have ten incisors above, the 

 middle ones being rather the longest, and eght below; three anterior 

 compressed grinders and four posterior bristlec grinders, the superior ones 

 triangular, and the inferior oblong, which, wi-'h the four canini, make in all 

 fifty teeth, the greatest number hitherto obierved in Quadrupeds. Their 

 tongue is papillated, and their tail prehei«ile and partly naked. Their 

 hinder thumb is long and very opposable to the other four toes, from which 

 circumstance these animals are sometimes styled Pedimana,- they have no 

 nail. Their extremely wide mouth, and great naked ears give them a 



