No. 50.] 19 
Order Marsupiata. 
A groupe of animals connected by striking peculiarities. About fifty 
species, arranged under twelve genera, have been observed in America, 
New-Holland, and the Indian Archipelago. A single species only has 
been noticed in the United States. 
Family Didelphidce. 
Didelphis virginiana. 
Order Rodentia. 
Comprising at present about seventy species ; but many more remain 
to be described. 
Family Musidce. 
*Sciurus leucotis, Gappar. Castor fiber. 
*S. hudsonius. Mus decumanus. 
*S. striatus. M. rattus. 
*S. niger. M. musculus. 
*S. vulpinus. *M. americanus, n. sp. 
*Pteromys volucella. *M. leucurus, n. sp. 
*Gerbillus americanus. *Arvicola riparius. 
Arctomys monax. *A. rufescens, n. sp. 
*A. empetra. *A. hirsutus, n. sp. 
*A. var. nigra. *A. oneida, n. sp. 
*riber zibethicus. 
Family Hystricidce. 
Hystrix dorsata. 
Family LeporidcB. 
*Lepus americanus. Lepus virginianus. 
The Order Edentata has no representative in the United States. 
Order Pachydermata. 
Family Equidce. 
Equus caballus, introduced. Equus major, fossil. 
E. asinus, introduced. 
Family Elephantidce. 
This groupe embraces eight living and twenty-one fossil species. 
The living species are found only on the eastern continent. 
Elephas primogenius. Mastodon giganteum. 
