DIDELPHYS. - 197 
dark colour of the upper part of the head. Dr. Elliott Coues, however, who has enjoyed 
unusual facilities for observation, and has made this animal a special object of study, 
finds that “all the characters assigned to these supposed species are to be found in 
specimens of D. virginianus from the same locality,” and that no grounds can be shown 
for separating the Opossums of the South-west even as a geographical race*. A com- 
parison of specimens in European Museums fully confirms Dr. Coues’s view, and leads 
me even to doubt whether D. virginianus will not eventually be found to grade into the 
South-American D. aurita. I have not yet, however, seen specimens from Nicaragua, 
where the two forms appear to meet, and therefore regard the range of the present 
species as extending from New Jersey and Pennsylvania southwards through the United 
States and Mexico to Guatemala, whence there are specimens in Mr. Salvin’s collections 
in the British Museum, and where, he informs me, it is common at Coban and else- 
where. 
So much has been written of the habits and manners of this well-known Opossum 
that it seems unnecessary here to do more than to refer to the excellent accounts of 
Audubon and Bachman and of Dr. Coues. 
2. Didelphys aurita. 
Didelphys aurita, Max. zu Wied, Beitr. Nat. Brasil. ii. p.395 (1826, descr. orig.)'; Frantzius, Arch. 
f. Naturg. xxxv. 1, p. 315”. 
Didelphys azare, Temminck, Monogr. de Mamm. i. p. 30 (1827, descr. orig.)?; Waterhouse, Nat. 
Hist. Mamm. i. p. 470, pl. xviii. fig. 2°. 
Zorro of Costa-Ricans *. 
Hab. Costa Rica (Frantzius? ; Hoffmann, Mus. Berol.)—Sovutn America to Uruguay *. 
I have followed Mr. Waterhouse in uniting Temminck’s Didelphys azare with Prince 
Maximilian’s D. aurita, but have retained the latter name as it has a year’s clear 
priority. Dr. Burmeister has rejected this identification, on the ground that D. aurita 
has the ears black, while those of the more southern species are white for their terminal 
half}. Buta specimen from Santa Fé de Bogota, Colombia, in the British Museum 
has the ears wholly white; and the observations of Dr. Coues on the North-American 
species show that no reliance can be placed on this character in discriminating the 
Opossums. In the colour and character of the fur a good deal of variety also exists, 
as has been observed by Dr. v. Frantzius in Costa Rica and by Dr. Hensel in Brazil {; 
in some few specimens (of which there are two, without locality, in the British 
Museum) the long stiff hairs are black instead of whitish. 
The range of Azara’s Opossum is more extensive than that of any of its congeners, 
extending from Uruguay, where it was obtained at Maldonado by Mr. Darwin, to Costa 
* Proc. Acad. Philad. 1871, pp. 15-18. t+ Thiere Brasil., Th. i. p. 131. t Infra, p. 198. 
