IO8 MAMMALS OF PENNSYLVANIA AND NEW JERSEY. 



the only lemming captured among a large number of voles. Quick and Butler 

 (supra citat. ) found them solely in such places in Indiana, saying : " This 

 mouse is found on hillsides in high, dry, blue grass pastures where flat stones 

 are irregularly scattered over the surface ; it especially prefers what are 

 known as ' woods pastures ' containing little or no undergrowth." He con- 

 tinues : " Cooper's mouse has been found breeding from February to Decem- 

 ber. It has never been known by the authors to bring forth more than four 

 young at a time. In all suckling females brought to our attention the mammae 

 have apparently been but four." A female taken by me Oct. 7, 1898, in 

 Clinton Co., Pa., contained five embryos. 



Quick and Butler say that the food of Cooper's mouse is chiefly stems of 

 blue grass and white clover, and the tuberous roots of "wild artichoke" 

 (Helianthus). 



Description of species. The cooperi form of lemming looks like a stump- 

 tailed, thick-set and undersized meadow mouse, Microtus pennsylvanicus, the 

 color being very similar but the fur is softer and fuller. The color above is 

 grizzled gray and yellowish-brown, thickly sprinkled with black, the belly a 

 frosted or silvery lead color. From an examination of specimens from In- 

 diana and Ohio I am inclined to class these as intergrades between cooperi 

 and gossi. The peculiar habits of Ohio Valley specimens strengthen this 

 view. The Beaver Co. specimen is nearer cooperi of course. In subspecies 

 stonei the size and body measurements are greater than in cooperi; the rela- 

 tive size of skull and teeth is much larger and the colors darker, especially 

 on the under side, with a strong wash of clay color over the abdomen and 

 breast not seen in cooperi. In these differences there is a significant parallel 

 to those distinguishing Evotomys gapperi and E. g. rhoadsi of the same 

 regions. Naturalists have recognized them in Evotomys but are slow to 

 accord the same to the Synaptomys under consideration. Dr. Merriam, who 

 later described a Synaptomys from Dismal Swamp, which differs from cooperi 

 in the same particulars as those given for stonei, ignores stonei, making it a 

 .synonym of cooperi. He makes his helaletes a full species, and a form he 

 named gossi from Kansas as a subspecies of his Dismal Swamp animal ! See 

 Merriam, Proc. Biol. Soc., Washn., 1896, p. 58, etc. For a resume of the 

 relations of these forms, see my article in the Proc. Acad. Nat. Sci., Phila., 



1897, PP- 305, 3<>7- 



Measurements. {cooperi) total length, 118 mm. (4^4 in.); tail vertebrae, 

 X 6 (^); hind foot, 19^ (34); skull, greatest length, 26.5 (i T V); greatest 

 width, 1 6 (Y%). (stonei), in same order, 125 (4J-f); 20 (ff); 20 (|f); 

 skull, 27.8 (i T V); 17-7 (U)- 



Specimens examined. Atlantic Co., May's Landing, 3 ; Cape May Co., 

 Tuckahoe, i ; Cumberland Co., Port Norris, 3. 



