■^Jjn"iiiijr>v)r.» X'. ' 'MJV 



20 



MONOGKAPnS OF NORTH AMERICAN RODENTIA. 



Ilorc th(3 figures arc 6.25 to 8.50. or nearly as 75 : 100; that is, tho tail ii» 

 about three-fourths the length of the head and body, at any rale. But, to be 

 fair to ourselves, we will take one other. No. 380G, a typical "occidentalis;" 

 here the figures arc 5.50 : 9.25, or about 59 : 100; that is, considerably undci 

 two-thirds thi; Iciigtii of the head and body. 



In other words : throughout the whole series, the tail (vertcbr«3) ranges 

 from about half as long to about four-fifths as long as bead and body ; in the 

 scries of true cinerea alone, the tail ranges from about one-half to about three- 

 fourths as long; in the series of "occidentalis", so called, the tail ranges from 

 less than two-thirds to about four-fifths as long; and the respective ranges 

 of the two series overlap each other by about as much as they difTer from 

 each other. Throughout, the variation is by insensible degrees; there is no 

 l)reak in the series. Obviously, therefore, the characters "caudal vcrtebraj 

 about as long as the trunk", as opj)osed to "caudal vertebroB considerably 

 shorter than the trunk" {Baird, op. cil. 487), fail to be diagnostic of two 

 species. 



The average tail is about two-thirds as long as the average body. 



Excluding No. 3898, which seems to be an abnormally small individual 

 if really adult, as it appears, the hind feet range from 1.40 to 1.85 in length, 

 a more customary range being 1.45 to 1.75; and the average settles very nearly 

 at 1.66 inches. The fore feet (not given in the table) are about one-third 

 of an inch long. 



The ears, measured from the notch in front, average a little over un inch 

 iu lengtli, ranging from 0.90 to 115. 



The whiskers are immensely long — the longest ones averaging nearly 4 

 inches. An idea of their length will be gained when we say that in one 

 specimen the distance between the tips of the outstretched whiskers is over 

 eight inches. 



The densely hairy tail of this animal, unique in the genus, early attracted 

 attention. The average tail is haired almost exactly as in Mi/oxus ; the hairs 

 increase in length, usually, from base to tip, and likewise, as in Mijoxus glis, 

 are more or less distichous in arrangement, so that the tail is flattened. In 

 some of the more heavily-haired tails, the resemblance to Tamias is striking; 

 and the hairiest of all even approach the condition of Sciurus itself, although 

 the shape is sul)terete rather than perfectly distichous. Thus, in No. 8314, 

 the hairs, pressed out flat, measure fullij three inches across, and the terminal 



