ORDER I. MARSUPIATA.
Family I. Didelphidæ.
(Opossums.)
The Opossums are small animals; the largest species scarcely equalling the domestic cat in size; while several are no larger than mice. They consist. of about twenty species, most of which, as has been already stated, inhabit South America. The whole constitute but one genus, with the exception of a single species, which, from its aquatic habits, indicated by broad webbed feet, has been separated, under the name of Cheironectes. They are distinguished by the great number of their teeth, which are arranged as follows: inc. 108; can. 1—11—1; false molars 3—33—3; molars 4—44—4; = 50. The incisors are small, and disposed some- what in the form of a semicircle; the canines are large and strong; the molars are crowned with sharp tubercles.
The feet have each five toes, armed with strong curved claws: the inner toe of the hind feet, however, is destitute of a claw, and is so placed as to be opposible to the others, thus constituting a true thumb,
Genus Dipereays. (Linn.)
To the characters enumerated above, we may add, that the tail in the true Opossums is more or
