86 
U. S. p. R. K. EXP. AND SURVEYS — 47TH PARALLEL. 
and collected a pile of fresh elder leaves, grass, and other food, together with a pair of broken 
iron hinges, brushes, bones, and other useless articles. We saw none until night, when they 
began to come in, and one climbed up to the bed, where, finding strangers in possession, he 
retired behind a rough board with which the joints of the logs were covered inside. Here he 
kept up a curious ticking sound for some time as if to show his anger at our intrusion. Having 
got a light, I watched him through a crack, but could not see how he made the " mysterious 
rapping." I then sharpened a stick and speared him with it as he sat. 
Afterwards a family of these rats took up their residence in a house where I lived. They 
had much the same mischievous habits as the common rat, but were less cunning. I could only 
catch them in traps by placing these in their way, as they refused cheese, bread, and other 
baits. We finally sixcceeded in killing the whole family of seven, which were all full grown. 
One poisoned itself by eating part of a bird skin preserved with arsenic. We afterwards found 
the nest made of oakum among a pile of flour barrels. A strong and disagreeable smell was 
perceptible about it. I never heard these rats squeal or make any sound when frightened or 
wounded. 
The largest specimen measured as follows: Male, head and body, 10 inches. Tail, 8|. 
Fore leg, 4f ; hind leg, 5:^- inches. Ear, 1 inch long, 1^^ wide. Female smaller. 
ARVICOLA TOWNSENDII, Bach man. 
Oregon Ground Mouse. 
.flivicola toionsendii, Bachman, J. A. N. Sc., Pliila. VIII, i, 1839, 60 Ib. In Townsend's Narrative, 1830, 315. 
Wagner, Wiegmann's Arcliiv. 1843, ii, 53 
AuD. & Bach. N. Am. Quad. HI, 1853, 209 ; pi. cxliv, fig. 1. 
Baird, Gen. Rep. Mammals, 1857, 527. 
Sp Ch. — Very large, (head and body 5j inches.) Ears large ; two-thirds as long as liind foot ; well furred. Tail, including 
the hairs, rather less than half the head and body; tlie tail vertebra? twice the length of hind foot. Thumb claw conspieious. 
Toes long ; one-tiiird the whole foot. Fur measuring a little over one-third of an inch, with a slight gloss. Above, dark 
fuscous brown, with but little yellowish brown visible. Sides paler; beneath, ashy white. Tail almost uniformly brown 
througliout. Feet liver brown. Skull, 1.27 -}- 71, or as 100 : 56. 
This meadow mouse is abundant on the meadows of Shoalwater bay, where it appears 
to have much the same habits as the species common in the Atlantic States. It forms summer 
nests of grass on the surface of the ground, commonly close to a root or log. Though I 
have frequently examined these, I never found young in them. It also makes galleries or 
paths through the grass, cutting off closely every stalk that stands in the way. During the 
annual floods which cover these meadows, great numbers of mice come out on the higher grounds, 
and thousands are doubtlessly drowned, which assists their many animated enemies in keeping 
down the numbers of a prolific and destructive animal. 
ARVICOLA OREGONI, Bachman. 
Jlrvicola oregoni, Bachman, J. A. N. Sc. Phila. VIII, i, 18.39, 60.— 1b. in Townsend's Narrative, 1839, 315. 
AuD. & Bach. N. Am. Quad. Ill, 1853, 232 ; pi. cxlvii, f 3. 
Baird, Gen. Rep. Mammals, 1857, 537. 
Sp. Ch. — About the size and shape of .^ruico/a puteiorio/i (35 inches). Skull .92. Fur sliort ( .3 of an inch). Head short, 
broad. Ears moderate, barely concealed, quite nalied, with a few scattered inconspicious white hairs. Antitragus small. 
Tail vertebrBB not one-third tlie head and body, longer than the head, one and one-half times the liind feet. Soles hairy for 
posterior third (.65 long). 
Above, dark brown, without any rufous tint. Hairs with obscure tips of yellowish brown. Beneath, lustrous hoary plum- 
beous ash. Tail corresponding in color to the body, but not sharply bicolored. Feet grayish brown. 
One specimen of this species was collected at Shoalwater bay. 
