MAMMALIA. 



4S5 



armed with five short claws ; hind feet horizontal, with five toes 

 enveloped in the skin. 



Trichecus rosmarus. — The Morse, or Walrus — Plate 

 XIV. fig. 5.— Described, vol. II. p. 39G. 



ORDER v.— MARSUPIALIA. 



In the sub-divisions of the different genera, the teeth vary 

 considerably. The young are all produced prematurely, or in 

 an early stage of developemcnt, and become attached to the 

 teats of the female, where they remain till they are fit to pro- 

 vide for themselves. The mammre are situated in the abdomi- 

 nal region, usually within a pouch, or fold of the skin, which 

 serves as a protection to the young. This pouch is supported 

 by two marsupial bones : thumb of the posterior extremities 

 mostly distinct and opposable to the fingers ; it, however, is 

 wanting in a few species. 



Almost all the species are inhabitants of New Holland and 

 South America. 



Division I. 



Having canine and insectivorous cheek teeth or grinders. 



Genus 1. — DiDELPHiS. — LinncEus. 



Generic Character. — Incisory teeth 'g", canines j-}, grinders 

 ?!? or 7I7 ; ^^^^^ "i^ '"' ^^' The two intermediate incisors in 

 the up^\)er jaw longer than the rest, and separated from them ; 

 they are very small and equal in the lower jaw; the canines are 

 strong compressed, and somewhat reflected ; the three first 

 grinders in the upper jaw are fiilse teeth, small and triangular ; 

 the remainder are insectivorous, or furnished with sharp points ; 

 the four first in the under jaw are also false and small ; and the 

 tliree others furnished with sharp tubercles ; head long and coni- 

 cal, and the muzzle acute ; ears large, rounded, and nearly 

 naked ; tongue aculeated. They are plantigrade in their loco- 

 motion ; feet with five toes, with long and bent nails ; tliumbs 

 of the hind feet long, opposable to the fingers, and without 

 nails ; tail long, half hairy and scaly ; hair hard and close ; 

 stomach simple. Inhabits America. 



