MAMMALS OF MARYLAND 



15 



visiting a nearby porch in the evenings to eat the pet food set out by 

 the owner for her cat. 



The opossum is a marsupial, distantly related to such animals as the 

 kangaroo and the koala of Australia. It gives birth to live young, but 

 the young are bom in a premature condition and are nursed in the 

 pouch or marsupium of the mother. When born, they are naked or 

 grublike in appearance, but the forelimbs are well enough developed 

 to be used for crawling into the pouch. Development is rapid in the 

 pouch, and within 4 to 5 weeks the young are ready to leave for short 

 periods. Llewellyn and Dale (1964, pp. 118-121) found that in Mary- 

 land the opossum begins to breed in early February, and young are 

 found in the pouch until August. Hartman (1952, p. 73) estimates the 

 gestation period as slightly under 13 days. Evidently two litters are 

 produced during a breeding season, but the first litter accounts for 

 the majority of yoimg. Llewellyn and Dale found that the average 

 number of young for 57 litters in pouch was 7.74. 



The opossum makes its home in almost any shelter where it can be 

 dry and safe from enemies. This may be under sheds or buildings, in 

 brush piles, or in holes in trees. In its eating habits the opossum is as 

 unselective as it is in finding a shelter. Hartman (1952, p. 62) lists 

 the frequency of foods taken in the following order: insects, fruits, 

 invertebrates (other than insects), mammals, reptiles, grains, birds, 

 and eggs. It also eats carrion. 



Specimens examined. — Montgomery County: Bethesda, 2; Boyds, 

 1; Cabin John, 3; Plummers Island, 2; no exact locality, 2. Prince 

 Georges Comity : Beltsville, 2; Bladensburg, 1 ; Branchville, 4; Green- 

 belt, 2; Laurel, 36; Patuxent Research Center, 2; T.B., 1. District of 

 Columbia: 25. 



Other records and reports. — Opo^ums have been killed in every 

 Maryland county (LeCompte, 1942). 



Remarks. — As noted by Gardner (1950, p. 65), Maryland opossums 

 are indistinguishable from Virginia topotypes of virginiana. 



Order INSECTIVORA (shrews, moles, etc.) 



Family SORICIDAE (shrews) 

 MASKED SHREW 

 Sorex cinereus Kerr 



This species closely resembles the southeastern shrew (Sorex longi- 

 rostris) and the pigmy shrew {Microsorex hoyi) . The differences 

 between the masked shrew and these other species are discussed under 

 the species accounts of the other two. 



There are two subspecies of Sorex cinereus in Maryland. These are: 



