320 MAMMALIA: GLIRES. — XLVIIL 
J. Mouse-like; length with tail 4 to 8 inches. 
g. Upper incisors grooved. . . . « « OCHETODON, 546. 
gg. Upper incisors not grooved; ears very vied . Caomys, 547. 
ff. Rat-like; length, with tail, a foot or more. . . . NEOTOMA, 548. 
ee. [Molars of upper jaw with ational in three series; soles naked; tail 
long, scant-haired or scaly. (Introduced species).]. . . . Mus. 
542. FIBER Cuvier. (Lat., beaver.) 
1039. F. zibethicus (L.). Muskrat. Color dark brown. L. 
225. T.11. N.Am.; everywhere. Largest of our Muride ; build- 
ing houses or burrows about streams and “ponds. (Lat., zibetha, the 
Civet, from the odor.) 
543. SYNAPTOMYS Baird. (cvvarra, to join; pis, mouse.) 
1040. S. cooperi Baird. Lemmrye Mouse. Mouse-color, gray- 
ish below; head very large with long whiskers; fur soft and long. 
L. 48. T. 3. Indiana (Brookville, Nashville) to Oregon and 
Alaska, a remarkable animal, between the field-mice and the lem- 
mings (Myodes). (To Dr. J. G. Cooper.) 
544. ARVICOLA Lacépéde. Fretp Mice. (Lat., arvum, 
field; colo, I inhabit.) 
a. Posterior upper molar with one exterior triangle and a posterior trefoil; 
middle upper molar with one internal triangle; front lower molar with 
two internal and one external triangle. 
b. Fore claws larger than hinder; fur dense, silky, mole-like; size small. 
(Pitymys McMurtrie.) 
1041. A. pinetorum Le Conte. Prine Mousse. Chestnut color, 
ashy below. L. 4%. T. 4. N.Y. to Ill and 8. (Lat., of the 
pines.) 
bb. Fore claws not larger than hinder; fur coarse, not glossy; size medium. 
(Pedomys Baird.) 
1042. A. austerus Le Conte. Grizzly brownish, rusty plumbe- 
ous below. L. 54. T.1. Mich. to Dak. and La. (Lat., harsh.) 
aa. Posterior upper molar with two external triangles and a posterior cres- 
cent; middle upper molar with two internal triangles; front lower 
molar with three internal and two or three lateral triangles; size large. 
(Mynomes Rafinesque.) 
1043. A. pennsylvanicus Ord. Mrapow Movss. Fore 
claws not longer than hind claws. Grayish brown, blackish 
mesially, hoary below. L. 53. T. 14. U.S., generally abun- 
dant; variable. (A. riparius Ord, a later name.) 
545. EVOTOMYS Coues. (ed, well; ods, ear; pods, mouse.) 
1044. BE. rutilus (Pallas). LoNneG-EARED Mouse. Color chest- 
nut, median line of back rusty-red; sides yellowish, belly dull 
white ; fur full and soft; ears prominent. L. 4}. T.14. North- 
