135 Richardson's Meadow Mouse
ARVICOLA RICHARDSONII.--AUD. and BACH. [Arvicola richardsonii] RICHARDSON'S MEADOW-MOUSE. [Water Vole] PLATE CXXXV.--FIG. 1. A. fuscus nigro tinctus, subtus cinereus, caerulescente-canus, auriculis mediocribus vellere fere conditis, cauda capite paullulum longiore.
CHARACTERS. Dull brown mixed with black, under parts bluish-gray; ears, of moderate size, nearly hidden by the fur; tail, a little longer than the head. SYNONYME. ARVICOLA RIPARIUS ? Ord. BANK MEADOW-MOUSE. Richardson, F. B. A., p. 120. DESCRIPTION. Head, rather large; incisors, large, much exposed, and projecting beyond the nose--upper, flattened anteriorly, marked with scarcely perceptible perpendicular grooves, and with a somewhat irregular and rather oblique cutting edge--lower, twice as long as the upper, and narrower, slightly curved, and rounded anteriorly; nose, thick and obtuse; whiskers, few and rather short; eyes, rather small; ears, ovate, rounded at the tip, not easily distinguishable until the surrounding fur is blown or moved aside. Body, more slender behind than at the shoulders, the hind-legs not being so far apart as the fore-legs; tail, rather short, tapering, and thinly covered with short hairs; fore-legs, short; feet, rather small, with four slender, well separated toes, and the rudiment of a thumb, which is armed with a minute nail; claws, small, compressed, and pointed; the third toe nearly equals the middle one, which is the longest. The hair of the toes projects over the claws but does not conceal them; the toes of the hind-feet are longer than those of the fore-feet, and their claws are somewhat longer; the inner one is the shortest, the second longer than the third, and the third longer than the fourth; the first and fifth are considerably shorter than the others, and are placed farther back. The fur on the back is about eight lines long, but not so soft and fine as in some other animals of the genus; it is nearly as long on the crown and cheeks, but is shorter and thinner on the chest and belly. COLOUR. Incisors, yellow; claws, white; whiskers, black; the whole dorsal aspect, including the shoulders and outsides of the thighs, is dull or dusky brown, proceeding from an intimate mixture of yellowish-brown and black, which colours are confined to the tips of the hairs and are so mingled as to produce a nearly uniform shade of colour without lustre. From the roots to near the tips, the fur has a uniform shining blackish-gray colour; on the ventral aspect (lower parts) it is bluish-gray; the margin of the upper lip, the chin, and the feet, are dull white; tail, dark brown above, lighter beneath, the two colours meeting by an even line. DIMENSIONS. Length of head and body, . . . . . . . . 7 inches. Length of tail, . . . . . . . . . . . 2 inches. HABITS. DRUMMOND, who procured this Meadow-Mouse, states that its habits are analogous to those of the common water-rat of Europe (Arvicola amphibius), with which it may be easily confounded, although the shortness of its tail may serve as a mark by which to distinguish it. It frequents moist meadows amongst the Rocky Mountains, and swims and dives well, taking to the water at once when pursued. All Meadow-Mice indeed are capital swimmers. We some time since amused ourselves watching one that had fallen into a circular cistern partly built up with stone and partly excavated out of the solid rock by blasting, and which was plastered with cement on the inside to make it water-tight. This cistern had about four feet of water in it. On one side there was a projecting rounded knob of stone some five or six inches long and about two wide, which slanted out of the water so that the upper edge of it was dry. Upon this little resting-place there was a large Arvicola Pennsylvanica (Wilson's Meadow-Mouse) seated very quietly, having probably tumbled in the preceding night. When we approached the edge and looked down into the clear element we at first did not observe the Rat, but as soon as we espied him he saw us, immediately dived, and swam around underneath the surface; quite rapidly; he soon arose, however, and regained his position on the ledge, and we determined to save him from what had been his impending fate--drowning or starving, or both. We procured a plank, and gently lowering one end of it towards the ledge, thought he would take advantage of the inclined plane thus afforded him, to come out; but in our awkwardness we suffered the plank to slip, and at the plash in the water the little fellow dived and swam around several times before he again returned to his resting place, where we now had the end of the board fixed, so that he could get upon it. As soon as he was on it, we began to raise the plank, but when we had him about three feet above the surface he dashed off into the water, making as pretty a dive as need be. He always looked quite dry, and not a hair of his coat was soiled or turned during these frequent immersions, and it was quite interesting to see the inquisitive looks he cast towards us, turning his head and appearing to have strong doubts whether we meant to help, or to make an end of him. We put down the plank again, and after two attempts, in both of which his timidity induced him to jump off it when he was nearly at the edge of the cistern, he at last reached the top, and in a moment disappeared amid the weeds and grasses around. GEOGRAPHICAL DISTRIBUTION. The only information we possess of the habitat of this animal is from DRUMMOND, who states that he captured it near the foot of the Rocky Mountains. GENERAL REMARKS. This species possesses longer and stronger incisors than any other American Rat of this genus; its mouth presenting in fact a miniature resemblance to that of the musk-rat. Although the Arvicola xanthognatha is a larger animal than the present, yet its incisors are not more than half as long as in this species. We have named this Arvicola in honour of Sir JOHN RICHARDSON, who in describing it (Fauna Boreali Americana, p. 120), applied to it, with a doubt, the name of Arvicola riparius, ORD, from which it differs so much as to render a comparison here unnecessary.