320 MAMMALIA: GLIRES. — XLVIII. 



f. Blouse-like; length with tail 4 to 8 inches. 



fj. Upper incisors grooved Ochetodon, 546. 



. Upper incisors not grooved; cars very large. . Calomys, 547. 



ff. Rat-like; length, with tail, a foot or more. . . . Neotoma, 548. 



ee. [Molars of upper jaw with tubercles in three series; soles naked; tail 



long, scant-haired or scaly. (Introduced species).] .... Mus. 



542. FIEER Cuvier. (Lat., beaver.) 



1039. F. zibethicua (L.). MtTSKRAT. Color dark brown. L. 

 22^. T. 11. N Am. ; everywhere. Largest of our Muridce ; build- 

 ing houses or burrows about streams and ponds. (Lat., zibetha, the 

 Civet, from the odor.) 



543. SYNAPTOMYS Baird. (avvairra, to join ; fivs, mouse.) 



1040. S. cooperi Baird. Lemming Mouse. Mouse-color, gray- 

 ish below; head very large with long whiskers; fur soft and long. 

 L. 4|. T. ;]. Indiana ( Brook ville, Nashville) to Oregon and 

 Alaska, a remarkable animal, between the field-mice and the lem- 

 mings (Myodes). (To Dr. J. G. Cooper.) 



544. ARVICOLA Lacepede. Field Mice. (Lat., arvum, 

 Held; colo, I inhabit.) 



(7. Posterior upper molar with one exterior triangle and a posterior trefoil; 

 middle upper molar wit li 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.) 



1 1 1 . A. pinetorum Le Conte. Pine Mouse. Chestnut color, 

 ashy below. L. 4f. T. \. X. Y. to DL and S. (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. b\. 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 Rarinesque.) 



1043. A. pennsylvanicus Ord. Meadow Mouse. Fore 

 claws not longer than hind claws. Grayish brown, blackish 

 mesial I v. hoary below. L. 5^. T. 1^. U. S., generally abun- 

 dant; variable. (.4. Hparius Ord, a later name.) 



545. EVOTOMYS Coues. (tv, well ; o£?, ear; fivs, mouse.) 



1044. E. rutilus (Pallas). Long-eXretj Mouse. Color chest- 

 nut, median line of hack rusty-red; sides yellowish, belly dull 

 white: fur full and soft; ears prominent. L. A\. T. \\. North- 



