2 1 6 Bulletin American Museum of Natural History. [Vol. XIV, 



MEASUREMENTS OF SKULLS. 



This pale northern form of Metachirus fuscogriseus is repre- 

 sented by a considerable number of specimens from the States of 

 Tabasco, Vera Cruz, Oaxaca, and Puebla. They vary a little 

 in coloration above, some being darker than others, but the dif- 

 ference is slight and partly seasonal. The lower surface varies 

 in general tone from yellowish white to deep buffy white. Young 

 specimens show gray areas on the sides of the abdomen, as in M. 

 fuscogriseus. All the adult males show more or less strongly a 

 sulphur yellow patch on the sides of the abdomen in front of the 

 thighs, this tint varying from pale yellowish to strong greenish 

 yellow. Several specimens differ from the average style through 

 the intensity of the buff coloration on the throat and sides of the 

 neck, which tint sometimes prevails as a strong buff wash over 

 most of the lower surface. The greenish yellow patch in front of 

 the thighs is characterized by a slightly different texture of the 

 hair, and is represented in the female by a clearer white than the 

 surrounding parts. Apparently it is a glandular area, and 

 most active in the breeding season, corresponding doubtless 

 to the glandular area on the lower throat and chest in Didelphis. 



