3*26 ANNUAL OF SCIENTIFIC DISCOVERY. 



THE MAMMALIA OF NORTH AMERICA. 



The total number of species of mammalia now recognized by Prof. 

 Baird, of the Smithsonian Institution, as inhabiting the North Ameri- 

 can continent, amounts to 220, of which he has himself examined 

 specimens, whilst there are 35 others more or less doubtful. This is a 

 vast increase no less than 70 species having been added as new to 

 Audubon and Bachman's list, the greater part being the result of the 

 Pacific Eailroad surveys. This, too, is exclusive of Cetacea, Pinni- 

 pedes and Bats. The first two of these groups can hardly be said to 

 belong to the land fauna of North America, but allowing fifteen 

 species for the Cheiroptera, on the authority of Prof. Leconte, the 

 whole number of positively recognized mammalia belonging to the 

 North American fauna is raised to 235, excluding Pinnipedes and 

 Cetaceans. Taking the several groups in the order in which they 

 stand in Prof. Baird's arrangement, we have first the Insectivora, con- 

 taining shrews and moles, together 26 species. Of the Carnivora, 

 the large number of 46 are recognized as North American, made up 

 of Felidse and Canidse, the Bassaris astuta of Mexico and Texas, 

 sole representative of the family Viverridce (civets), 23 Mustelidce, 

 and 5 species of Ursidce. This is exclusive of several species estab- 

 lished by previous writers, but which Prof. Baird has, with much judg- 

 ment, reduced to the rank of local varieties such as the Canis 

 nubilus of Say, and the Felis maculata of Horsfield and Vigors. 



The Marsupialia in the northern portion of the American conti- 

 nent are represented by two species of the genus Didelphis, commonly 

 known as " Opossums." 



The Rodents are, again, extremely numerous. In the first place, 

 the Squirrels of different genera, with the Marmots (so called), 

 Prairie-dogs and Beavers, make up no less than 4] members of the 

 family Sciuridce. The Saccomyidce, or Pouched Mice, which, in ac- 

 cordance with Mr. TVaterhouse's views, but in opposition to those of 

 Professor Brandt, are grouped together, next follow, and are consid- 

 ered by Professor Baird as " one of the most natural families of Ro- 

 dentia, although the component genera have been widely separated 

 by different authors. In the external cheek-pouches," he remarks, 

 " there is no other family which exhibits any approach to it. These 

 open outside of the mouth, and are of variable depth, and lined with 

 short hairs to the bottom. When inverted and dried, they look like 

 sacs on each side of the head." Of these peculiar animals, the range 

 of which is confined to Northern America and the Antilles, 21 species 

 are enumerated, as appertinent to the fauna of the United States. 

 Two Porcupines of the North American form Erethizon are the only 

 Hystricidce met with in this part of the world ; but there are no less 

 than 52 Muridce of varied forms: and 13 Hares and Rabbits, with a 

 single Layomys, give 14 species of the family Leporidce. Altogether, 

 therefore, the order Rodentia in North America, as elsewhere, plays 

 a most important part as regards numbers, embracing 130 species 

 more than half the whole number of mammals known to occur. 



The order Edentata is represented within the limits of the United 

 States by a single straggling species of Armadillo, which occurs within 



