136 GRADATION OF ORDERS. MARSUPIALIA. 



necessary to follow some order in the more particular description 

 of them ; and the following is probably the most correct, in 

 regard especially to the grade which the different groups possess 

 in the scale. " I. BIMANA. II. QUADRUMANA. III. CHEIRO- 

 PTERA. IV. INSECTIVORA. V. CARNIVORA. VI. CETACEA. 

 VII. PACHYDERMATA. VIII. RUMINANTIA. IX. EDENTATA. 

 X. RODENTIA. Tims from Man we pass to the Quadrumana 

 by the Apes which most nearly resemble him in bodily struc- 

 ture. From these we descend to the Lemurs, in which the 

 teeth show an insectivorous character, and certain species exhi- 

 bit a tendency to the formation of organs of flight ; by which 

 characters we are conducted to the Cheiroptera, or Bats. From 

 the insectivorous forms of these, the transition is not difficult to 

 the proper Insectivora ; which, again, lead us to the Carnivora; 

 and these, by their aquatic species, to the Cetacea. From the 

 Cetacea we naturally pass to the whale-like Pachydermata ; 

 and then, through the terrestrial tribes of these, to certain 

 species which conduct us to the Ruminants. The Edentata and 

 Rodentia are not closely connected, by any existing species, with 

 either of the two last orders ; but there are certain fossil forms, 

 which seem to link them to both. 



126. The division of non-placental Mammalia contains two 

 orders only, which are chiefly distinguished by certain peculiarities 

 affecting the reproductive apparatus. 



XI. MARSUPIALIA, or pouched animals ; being those in which 

 the young are carried during the early part of their lives, in a 

 marsupium, formed by folds of the skin of the abdomen, which 

 are supported by peculiar bones. The species included in this 

 group differ greatly among each other, both in the general form 

 of their bodies, and in the conformation of their teeth and diges- 

 tive apparatus. Indeed they bear, in these respects, a striking 

 resemblance to animals of different orders among the truly vivi- 

 parous Mammals. Thus, the Opossums have an opposable thumb 

 on all four extremities ; so that they are truly quadrumanous, or 

 four-handed. Others, again, bear a close resemblance to the 

 Carnivora ; and others to the Rodentia ; so that the order Mar- 

 supialia was really distributed amongst these groups, when the 



