1^ 



MUBID^— AEVICOLIN^— AKVICOLA BIPAKIUS. 



223 



llic longest hardly equaling the head; the obtuse muzzle is entirely furry, 

 except the small emarginate papilla on which the nares open. 



The fur of this species is remarkable for its shortness, closeness, and 

 lustre, approaching that of the mole, and in fact betraying the species at first 

 glance. The coloration, too, is singularly uniform ; not, indeed, in its shade, 

 but in the evenness with which the shade, whatever this may be, is distrib- 

 uted over all the upper parts, without the slightest variegation. The dense 

 texture and even coloration of the pelage are both due to the same thing : 

 to lack of the longer bristly hairs that in nearly all other species are distrib- 

 uted through the fur of the upper parts. 



The precise shade of the upper parts is subject to variation parallel with 

 and as great as that we have demonstrated for A. riparim. A part is due 

 probably to individual and seasonal variability, but more is owing, we believe, 

 to climatic influences, since diflTerent localities seem productive of local races 

 that appear tolerably constant In what may be called the typical coloration, 

 prevailing in the Southern Atlantic States, the animal is of a rich glossy 

 chestnut or light bay, which shades into slightly more yellowish-brown on 

 the sides before this glides into the color of the under parts. The latter is a 

 deep pluml)eous, strongly silvered over with hoary ash. Some Pennsylvania 

 skins are identical with this ; others (among them No. 4714, type of "apella") 

 , are much darker, and more truly a dull brown than a bay. The same is the 

 case with some typical " scalopsoides " from southern New England, and 

 generally mountainous as well as northerly specimens are apt to be the 

 darkest. The fine large Illinois series, gathered by the lamented Kennicott, 

 are among tiie darkest of the whole lot; some of them, in fact, betraying 

 little of the characteristic chestnut. This is the chief basis of the suggested 

 name "kennirottii" in Baird, op. cit. 5il. One curious specimen. No. 2876, 

 from South Carolina, also mentioned by Baird, /. c, is dark-rufous along the 

 back, with the sides rich fulvous or orange, appearing in marked contrast, as 

 two lateral longitudinal stripes. No. 978, from Ohio, a very young animal, 

 shows something of the same peculiarity, which we have also seen in occa- 

 sional samples of other species, as in No. 2056 of riparius, from Halifax, N. 

 S., and No. 4172, from Fort Crook, Cal. Very young animals normally differ 

 from the adults in being plain mouse-gray, with hardly a trace of bay (No. 

 744, for example). 



The western specimens we tabulate are interesting as greatly extending 



