2 I'4 Bulletin American Museum of Natural History. [Vol. XIV, 



adult specimens are similar in coloration to those from Grey town, 

 except in the case of one very old male, distinguished by its large 

 size and a strong orange-rufous tinge on the cheeks, sides of the 

 neck, and throat. This series shows, as in the case of Didelphis, 

 that ihe animal increases greatly in size after reaching maturity. 

 In the younger specimens the buff color of the ventral surface is 

 restricted to the chest and the lower abdominal region, the two 

 areas being connected by a narrow buffy median band, the sides 

 of the abdomen being more or less plumbeous, with the tips of the 

 hairs lighter, a condition often seen in various species of Muridae, 

 especially in Neotoma, Oryzomys and allied genera. The adult 

 males are distinguished in the breeding season by a pale yellowish 

 patch on the sides of the lower abdomen just in front of the 

 thighs, the corresponding area in the female being whitish, and 

 the hair at these points is of a little different texture from that of 

 the surrounding parts. 



EXTERNAL MEASUREMENTS. 



Fifty miles from Bluefields, on the Escondido River. 



MEASUREMENTS OF SKULLS. 



