TIIK BLACK 



41)5 



iiidividuaK* now in the Stnlc Miiseuni at Indianapolis, was taken 

 at New Albany, Deeeniher H, 1904. It doubtless reached this plaee 

 in a shipment of ^^'oods from some southern port. 



Ilahifs.— The habits of this species nvv, similar to those of the 

 (^omiiiou rat. That is probably the reason the two species cannot 

 exist together and the larger drives out the smaller. This species 

 is said to be less of a nuisance, however, because it is smaller and 

 less aggressive. The black and white rats, often kept as pets and 

 for psychological and bacteriological experiments, are probably de- 

 rived from this species. 



Genus Peromyscl'S Gloger. 



Pcromijscus Gloger, Gemein. Hand und Ililfsbuch d. Naturge- 

 schichte. Vol. I, p. 95, 1842 {Hcspcromys of Baird. Calomys 

 of Evermann and Butler.). Osgood, North American Fauna 

 No. 28, 1909. 



Dental Formula.—l, C, Pm, I^I^; M, |E| = 16. 



Generic characters. — Size and form similar to the house mouse 

 {Mus) from which the genus is distinguished by having two rows 

 of tubercles on the molar teeth instead of three and by the white 

 under parts of the body. No other mice recorded from Indiana 

 are apt to ])e confused with those of the genus Peromyscus, although 

 there are genera in the south and west which resemble it. Of these 

 the little harvest mouse (Rcithrodontoniijs) may yet be found in 

 the State. It is distinguished by its small size and grooved upper 

 incisors. 



The range of this genus is limited to North America and the 

 extreme northern corner of South America. The species are among 

 the most plastic of any mammals known, varying with every change 

 of climate and physical surroundings. IMore than 150 species and 

 subspecies are known. Three forms are recorded from Indiana 

 and a fourth may sometime ])e found in the southern part of the 

 State. They m^y be distinguished ])y the following key: 



Color of both yoniiiir and adults, brijjht golden or fnlvons. 



nuttalli, appendix. 



Color of young, dnll hhiisli gray, of adults, fawn color, grayish or brown- 

 ish. 



* This may possibly he a roof rat, Mus alexandrinus Geoffrey, often classed as 

 a variety of the black rat. The specimen is stuffed out of proportion and I have 

 had no chance to examine the skull. l)iit it seems to agree perfectly with the black 

 rat In color. The roof rat is common in parts of the southern states and might 

 easily have been carried up th(> river on a boat. 



