1901.] Allen, Opossums of the Genus Didelphis. 175 



Didelphis richmondi, sp. nov. 



Type, No. ffj|, U. S. National Museum, ? adult, Greytown, Nicaragua, 

 Feb. 7, 1892 ; collected by Dr. Charles W. Richmond. 



Adult. The long bristly overhair is black and yellowish white, that of the 

 nape and shoulders mainly black, in contrast with that of the rest of the dorsal 

 surface ; generally the white overhair is more abundant than the black ; under- 

 fur coarse, yellowish white for the basal two thirds tipped with black ; extreme 

 basal half dingy greenish orange ; sides of the head to the posterior base of the 

 ears soiled pale buffy white, separated by a distinct median stripe of black run- 

 ning forward to a little beyond the eyes ; an ocular band of blackish, running 

 from the ear to the base of the whiskers ; cheeks soiled buffy white ; underparts 

 with the pectoral area, including the sides of the neck, buffy at the surface, 

 with the pelage brownish yellow of the basal two thirds ; legs and feet black ; 

 nails yellowish white ; ears wholly black ; tail with the basal half black, the rest 

 flesh- color. 



Young. A young specimen, about one fourth grown, is similar to the adult, 

 except that the coarse overhair is more abundant, and it presents the same 

 contrast of black predominating anteriorly and yellowish white posteriorly. 

 The underfur is stained deep orange buff as in the adult ; lower parts deeper 

 buff than in the adults without the dusky tipping to the hairs. 



Measurements of type. Total length, 948 mm.; head and body, 471 ; tail, 

 477 ; tarsus, 70. Skull, total length, 114 ; basal length, 104 ; nasals, 54 ; zygo- 

 matic breadth, 55 ; length of palate, 65 ; upper toothrow, 37.4. (For additional 

 measurements see Table V.) 



This species is based on four skins with skulls and two addi- 

 tional skulls, from Greytown, Nicaragua, collected by Dr. Charles 

 W. Richmond, for whom the species is named. The skins 

 comprise three adult females and a young male about one 

 fourth grown. Three of the specimens are quite similar in 

 coloration, having a well defined median black stripe on the 

 head and a dusky stripe from the ear through the eye to the base 

 of the whiskers, between which markings the color is pale buffy 

 white. Another adult in very worn pelage is similar in markings, 

 but almost entirely lacks the long overhair, which has apparently 

 been worn off. I also refer here two very young specimens from 

 Costa Rica, formerly identified by me as D. aurita, on account 

 of the yellow color of the ears, and also six adults from Costa 

 Rica, collected by the late Dr. Gabb near San Jose. 



Didelphis richmondi differs from D. marsupialis in the more 

 slender form of the skull, which is long and narrow, with very 

 long nasals, and in the great length of the tail. It also differs in 



