128 . CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



buffy on toes dorsally, as in No. 19174; or having black hairs 

 insprinkled and a darker shade of buffy, as in Nos. 19974 and 

 19983; hairs about bases of claws often exceeding claws in 

 length. Sides of body paler than back ; the spiny black hairs 

 fewer jn number. In a typical example (No. 19174) the color 

 grades from near orange-cinnamon dorsally to light ochraceous- 

 buff laterally. 



The peculiarities in coloration of a specimen ' collected at 

 Meadows, Lane County, Oregon, have already been commented 

 on in the literature (Miller, 1897a, p. 85; Merriam, 1901, p. 

 126; and see below, p. 131). 



(3) Ventral coloration 



White, sometimes with plumbeous bases of hairs showing 

 through to some extent, often with the faintest possible wash 

 of buffy. In adult females the positions of the two pairs of 

 abdominal mammae are marked by sparsely-haired circular 

 patches a quarter to one-half inch in diameter. Hairs of 

 throat and of nipple patches have no plumbeous bases. 

 Sometimes hairs posteriorly on belly in vicinity of nipple 

 patches also lack plumbeous bases. 



Tail varying in coloration, in different examples, from 

 pinkish-cinnamon to blackish-brown. Although there is in 

 some specimens the faintest possible tendency toward ventral 

 paling, in a large majority there is no discernible difference 

 in coloration between the upper and lower sides. Most of the 

 series have the tail tipped with a pencil of blackish-brown hairs. 

 In No. 21153 all the tail except the tip is pinkish-cinnamon. 

 Consequently the blackish-brown tip is very conspicuous. 

 Ordinarily the general tail coloration is so dark that no 

 contrast is observable. 



(4) Length of tail 



Miller (1897a, p. 79), in his key to the genus Phenacomys, 

 sets off longicaudits as having a tail forty per cent of its total 

 lengthj while the remaining species, including ungava, lati- 

 mamis, intermedius, prchlei, and orophilus, are grouped as 

 having tails only twenty-five per cent of total length. 



An examination of the available series of thirty-seven speci- 

 mens of longicaudus, in connection with the study of the other 

 examples of Phenacomys at hand and of all published meas- 

 urements, enables the writer to confirm the validity of this 



