i8o Field Museum of Natural History — Zoology, Vol. XL 



Genus EPIMYS Trouessart. 



Epimys Trouessart, Catal. Mamm. Viv. et Foss., Bull. Soc. d'Etudes, 

 Sci. d'Angers, X, 1881, p. 117. Type, by subsequent designation, 

 Mus rattus Linn. Miller, Proc. Biol. Soc. Wash., XXIII, 1910, p. 58. 



Front teeth (incisors) 2 in each jaw; no premolars; upper molars 

 or grinding teeth having tubercles on crowns arranged in three lon- 

 gitudinal rows as in Mus\ "molars slightly graduated in size from first 

 to third, the anterior tooth not tending to assume the main function 

 of the toothrow, the posterior tooth not tending to disappear, enamel 

 folding of upper molars directly referable to a simple g-cusped pattern 

 and its reductions, the outher margin of M^ and M^ never with more 

 than three cusps, the inner margin of same teeth never with more 

 than 2 cusps, M^ usually with 5 roots, its first lamina not distorted 

 by the backward displacement of antero-internal tubercle ; upper incisor 

 moderately compressed, set at such an angle that its outer side is 

 worn smoothly away by action of lower teeth." (Miller.) 



Epimys norvegicus (Erxleben). 

 Norway Rat. Brown Rat. House Rat. 



[Mus\ norvegicus Erxleben, vSyst. Regni Anim., I, 1777, p. 381. Jackson, Bull. 



Wis. Nat. Hist. Soc, VI, 1908, p. 20 (Wisconsin). Hahn, Ann. Rept. Dept. 



Geol. & Nat. Resources Ind., 1908 (1909), p. 492 (Indiana). 

 Mus decuwanus Kennicott, Trans. 111. State Agr. vSoc, I, 1853-54 (1855), p. 579 



(Illinois). Rhoads, Proc. Acad. Nat. Sci. Phila., 1896 (1897), p. 192 (Tennessee). 

 Neotoma floridana Wood, Bull. 111. State Lab. Nat. Hist., VIII, 1910, p. 550. 



Type locality — ■ Norway. 



Distribution — Nearly cosmopolitan. In America generally distributed 



throughout the country wherever there are habitations of men. 

 Description — Hair coarse; general color brown, darkest on middle of 



back; under parts pale grayish brown; tail scaly and very scantily 



haired; tail not longer than. head and body, usually less. 

 Measurements — ■ Total length, about 15.50 in. (394 mm.) ; tail vertebrae, 



about 7.12 in. (180 mm.); hind foot, 1.75 in. (45. mm). 



This species was introduced in North America some time during the 

 latter part of the eighteenth century and in spite of all attempts to 

 exterminate it, it has thrived and increased to a remarkable degree. Of 

 its habits little need be said. They are destructive to property and in 

 agricultural districts consume a large amount of grain and food of every 

 kind wherever they can find it. They are also objectionable from an 



