90 



NORTH AMERICANi FAUNA 66 



Specimens examined. — Anne Arundel County: South River, at U.S. 

 Route 50, 1. Charles County: Nanjemoy Creek, 5. Prince Georges 

 County: Oxon Hill, 2 miles NW, 2. Worcester County : Ocean City, 4 

 and 5 miles S ( Assateague Island) , 2 ; West Ocean City, 4. 



Other records and reports. — Dorchester County: Blackwater Na- 

 tional Wildlife Refuge (Harris, 1953) . 



EASTERN HARVEST MOUSE 

 Reithrodontomys humulis virginianus A. H. Howell 



Reithrodontomys humulis virginianus A. H. Howell, Jour. Mammal., 

 21 (3) : 346, 13 August 1940. 

 Type locality. — Amelia, Va. 



General distribution. — Known from central Virginia north to Maryland. Exact 

 northern limits of range unknown. 



Distribution in Maryland. — Rare in Maryland; probably occurs 

 only in the Western Shore and southern Piedmont sections. 



Distinguishing characteristics. — Teeth 1/1, 0/0, 0/0, 3/3, = 16; upper 

 incisors with conspicuous grooves; mouselike in form; tail about half 

 total length; coloration grayish-brown above with a distinct band of 

 blackish along the median line; sides of head and body paler, more or 

 less washed with light pinkish cinnamon, this color forming a definite 

 lateral line next to the belly; underparts grayish white; tail bicolored, 

 fuscous above, grayish white below; ears fuscous, feet white. 



This species closely resembles the house mouse (Mu^ musculus) in 

 general appearance, but may readily be distinguished from that species 

 by the deeply grooved upper incisors. In the eastern United States 

 the harvest mouse is the only long-tailed cricetine rodent with grooved 

 incisors. 



Measurements. — An adult female from Takoma Park (near Riggs 

 Mill), Prince Georges County, measures as follows: Total length 132; 

 tail 59 ; hind foot 15.5 ; ear 12 ; greatest length of skull 20.0 ; zygomatic 

 breadth 10.1 ; least interorbital breadth 2.9 ; upper molar toothrow 2.5. 



Howell (1940, p. 346) gives external measui-ements of 10 specimens 

 from the type locality as follows: Total length 117.2 (110-125) ; tail 

 vertebrae 51.8 (45-56) ; hind foot 16.2. The greatest length of skull 

 of these 10 specimens is 18.7 (18.3-19.1) . It can be seen that the Mary- 

 land specimen is considerably larger both externally and in the great- 

 est length of the skull than topotypes of the subspecies from Amelia, 

 Va. 



Habitat amd hahits. — The harvest mouse prefers nonforested land, 

 particularly cultivated fields where grain crops are growing. It seems 

 to be equally at home in dry fields or in bogs, provided there is thick 

 growth of tall grasses or sedges. 



