86 IT. S. p. R. R. EXP. AKD SURVEYS — 47TH PARALLEL. 



and collected a pile of fresli 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 s^jeared 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 succeeded 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, 4|; hind leg, 5^ inclies. Ear, 1 inch long, 1^ wide. Female smaller. 



ARVICOLA TOWNSENDII, Bach man. 



Oregon Ground Mouse. 



Jlrvicola toicnsendii, Bachman, J. A. N. Sc, Phila. VIII, i, 1839, G8 — Ib. In Townseiid's Narrative, 1830, 315. 

 Wagner, Wiegmann's Archiv. 1843, ii, 53 

 AuD. & Bach N. Am. Quad. Il[, 1853, 209 ; pi. cxliv, fig. 1. 

 Baird, Gen. Rep. Mammals, 1857, 527. 



Sp, Ch. — Very large, (head and body 5i inches.) Ears large : two-thirds as long as hind foot ; well furred. Tail, including 

 the hairs, rather less than half the head and body; the tail vertebra! twice the length of hind foot. Tliunib claw conspicious. 

 Toes long; one-third 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 

 throughout. 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. 



Jlrmcola oregoni, Bachman, J. A. N. Sc. Phila. VIII, i, 1839, 60. — Ib. in Townsend's Narrative, 1839, 315. 

 AuD. & Bach. N. Am. Quad. Ill, 1853, 232 ; pi. cxlvii, f 3. 

 Baied, Gen. Rep. Mammals, 1857, 537. 



Sp. Ch. — About the size and shape of .4rDico/apinctoriim (31 inches). Skull .92. Fur short (.3 of an inch). Head short, 

 broad. Ears moderate, barely concealed, quite naked, with a few scattered inconspicious white hairs. Antitragus small. 

 Tail vertebroe not one-third the head and body, longer than the head, one and one-half times the hind 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. 



