MAMMALIA. 469 
usual, on vegetable substances. One species only is described, and belongs 
to the northwest portion of North America, the sewellel of Lewis and Clark 
(A. leporina). A second species is indicated, if the characters alluded 
to by the author are not differences occurring in the young. 
The genus Arctomys (the marmots) has, like the squirrels, five molars 
above and four below, all of them bristled with points; accordingly some 
species are inclined to eat flesh and feed upon insects as well as grass. As 
to their general form, the marmots are the very reverse of the squirrels, 
being heavy, provided with short legs, a middle-sized or short hairy tail, 
and a large, flat head, passing the winter in a state of torpor and shut up in 
deep holes, the entrance of which they close with a heap of grass. They 
live in societies, and are easily tamed. The alpine marmot, A. marmotta or 
alpinus (pl. 118, jig. 11), is about the size of the hare. Four species are 
described from North America, among which is the common Maryland mar- 
mot, or ground-hog (A. monazx) of the northern, eastern, and middle states. 
~The genus Spermophilus possesses cheek pouches, two incisors above 
and below, and five molars above and four below, exactly as in the ground 
squirrels; but whilst the external appearance of the latter is more like 
that of squirrel proper (Sciwrus), the general appearance of Spermophilus 
is more that of the marmots, from which it is distinguished by the dentition. 
The molars are more narrow transversely than longitudinally. The ears 
are generally short. The feet are of moderate length, adapted for walking 
on the ground; the nails are inferior in size to those of the marmots, and 
less hooked than those of the squirrels. ‘There are four toes to the fore 
feet, with the rudiment of a thumb protected by a blunt nail; the hind feet 
have five toes. The tail is always shorter than the body. The form of the 
body is rather slender, and possesses a degree of lightness and agility 
‘approaching the activity of the squirrels. Twelve species of this genus 
‘are known to exist in North America, three in Europe, and a few in 
Asia and Africa, if some of the latter are not to be referred to the genus 
Arctomys. 
In North America they are commonly known by the names of marmot 
squirrels, prairie marmot or prairie dog, tawny American marmot, leopard 
marmot, small grey squirrel (Lewis and Clark), and other similar appella- 
tions more or less arbitrary. They chiefly inhabit the northern regions. 
The following is an extract from Say, in Long’s Expedition to the Rocky 
Mountains, on the habits of the prairie dog (S. ludovicianus): 
“This interesting and sprightly little animal has received the name of 
‘prairie dog, from a fancied resemblance of its warning ery to the hurried 
barking of a small dog. The sound may be imitated by the pronunciation 
of the syllable ‘chek, chek, chek!’ in a sibillated manner, and in rapid 
‘succession, by propelling the breath between the tip of the tongue and the 
roof of the mouth. As particular places are in general occupied by the 
burrows of these animals, such assemblages of dwellings are denominated 
prairie dog villages by the hunters. They vary widely in extent, some 
being confined to an area of a few miles, others bounded by a cireum- 
ference of many miles. Only one of these villages occurred between the 
ICONOGRAPHIC ENCYCLOP£DIA.—VOL, II. 43 673 
