322 CALIFORNIA ACADEMY OF SCIENCES [ Proc. 4TH Ser. 
Epimys norvegicus (Erxleben) 
Norway Rat 
Original description—‘Mus norvegicus Erxleben, Syst. 
Reoni Anim 777.) sole 
Type locality—“Norway.” 
Synonyms—Brown Rat, part; Wharf Rat; Mus decumanus. 
Range—Almost everywhere in the settled portions of the 
state, chiefly in towns and cities. In the San Joaquin and 
Sacramento valleys, rats have invaded marshy tracts and occur 
along sloughs far from human habitations. ‘This is the most 
abundant species of non-native mammal outside of the house 
mouse. 
Epimys rattus (Linnaeus) 
Black Rat 
Original description—Mus rattus Linnaeus, Syst. Nat.,1, 
H/T, 105 (OM, 
Type locality—Sweden. 
Range—Occurs in relatively small numbers in San Francisco 
and neighboring cities of the San Francisco Bay region. Not 
native. 
Epimys alexandrinus (Geoffroy) 
Roof Rat 
Original description—‘“Mus alexandrinus Geoffroy, De- 
scription de l’Egypte, Mammiferes, 1818, p. 733.” 
Type locality—“Alexandria, Egypt.” 
Synonym—Brown Rat, part. 
Range—Occurs commonly in the larger cities of west-cen- 
tral California. Not native. 
* 
Mus musculus musculus Linnaeus 
House Mouse 
Original description—Mus musculus Linnaeus, Syst. Nat., 
LiLo spay: 
Type locality—Sweden. 
Range—Practically throughout the state around human 
settlements ; in the thickest settled valleys occurs widely over 
uncultivated land, often a mile or more from the nearest build- 
