1899-] Allen, New Rodents from Colombia and Venezuela. 215 



phase, and the individual hairs of the dorsal region are lustrous 

 red, entirely lacking the black annulations. In the next stage the 

 long red hairs form a broad mantle, covering the shoulders and 

 extending along the sides, while the head and back are mixed 

 red and black, the hairs over these portions being shorter and 

 conspicuously annulated with black. In the extreme olivaceous 

 phase the pelage is much shorter, and the whole dorsal surface 

 is covered with annulated red and black hairs, while the feet, the 

 forearms, outer edge of the thighs, and a narrow line bordering 

 the white of the ventral surface are red. About ten of the speci- 

 mens are distinctly in the clear red phase, and about the same 

 number are in the annulated olivaceous phase, the remaining one 

 half to two thirds being in various stages of transition between 

 the two. In all of these the color of the dorsal surface extends 

 for a short distance on to the base of the tail ; in the wholly red 

 specimens the basal portion of the tail is red, like the back. 



The individual variation consists mainly in intensity of the red 

 of the general pelage, this varying from light yellowish red to 

 dark or chestnut red. The tail is exceedingly variable in respect 

 to the amount of black near the base of the hairs. The greater 

 part of the specimens, irrespective of variations in the color of 

 the body, have all the tail hairs entirely red to the base ; in others 

 a portion of the hairs are broadly annulated with black near the 

 base, the number of these hairs and the width of the black band 

 increasing from the base of the tail toward the tip. This de- 

 velopment of black in the tail varies, in specimens where black 

 is present, from a faint trace, most prenounced on the outer third 

 of the tail, to a conspicuous broad band, visible at the surface 

 without parting the hairs, or at least producing a clouded effect 

 near the tip. As thus developed the black forms a broad con- 

 cealed subbasal zone, occupying from one fifth to one third the 

 length of the hairs, which are red at base and tip, the overlying 

 hairs on both surfaces of the tail being intense deep red. 



Individual variation in color is also well shown in a series of 

 6 one-fourth to one-third grown young. One of these was taken 

 in June, four in July (July 7-14), and one Nov. 18. The June 

 and July specimens resemble the red phase of the adults, while 

 the November specimen resembles the mixed red and black 

 phase. 



