1904.] Allen, Mammals from Santa Marta, Colombia. 433 



'winter' or breeding pelage, in which the hairs are long, 

 shining intense uniform rufous, without annulations of black, 

 shown in perfection by only about one specimen in ten of the 

 present series. The olivaceous phase is the opposite extreme, 

 the post-breeding pelage, shown in perfection by still fewer 

 examples. In this pelage the whole dorsal area, including 

 the head, flanks, feet, and the basal inch and a half to two 

 inches of the tail, all of the body pelage except the fulvous 

 chin and throat and the white of the belly and inside of the 

 limbs and the apical three-fourths to four-fifths of the tail, 

 is olivaceous, the hairs individually being dark plumbeous 

 for the basal third, then fulvous narrowly ringed subapically 

 with black, giving an olivaceous general effect. The change, 

 as usual, begins on the feet, soon involving the inside of the 

 fore arms and inside of the thighs, and later the whole of the 

 fore limbs and outside of the shoulders ; simultaneously there 

 is also developed a bright rufous lateral line ; the new pelage 

 now rapidly advances up the sides of the chest and shoulders, 

 meeting on the median line and then extending forward over 

 the head and backward to the base of the tail, the rump, basal 

 portion of the tail, and the top of the head being the parts 

 last to acquire the brilliant rufous of the breeding pelage. 

 The greater part of the specimens of the present series (taken 

 at various dates from June 20 to August 3, but nearly all in 

 July) are in various stages of the change, often showing a 

 clear and unmistakable line of demarkation between the 

 two pelages. The most olivaceous specimen of the series was 

 taken March 12; the most intensely and uniformly rufous 

 specimens were taken July 4, 6, and 29. The seasonal 

 change in color, through moult, is perfectly parallel to that 

 in the North American Sciurus hudsonicus group. 



There is evidently considerable individual variation, and 

 it seems probable that many specimens never reach the com- 

 plete intense stage of rufous, but have the hairs of the head, 

 lower back, rump, and the base of the tail red, subapically 

 ringed narrowly with black, the black annulations being more 

 or less visible as a part of the surface color. The tail hairs 

 are generally uniform deep red from tip to base, but in quite 



