1902.] Allen, Opossums of the Genus Didelphis. 253 



the base with the rest black, 1 whereas just the opposite is 

 true, as noted by Wagner and Hensel. 



In 1826 Wied (Beitr. zur Naturg. von Brasilien, II, 1826, 

 pp. 387-400) recognized what he considered to be two species 

 of true Didelphis from southern Brazil, one of which he 

 identified with D. marsupialis Linn., and the other he pro- 

 visionally described as new, under the name Didelphys aurita, 

 on the basis of a single female specimen from Villa Vigoza, 

 Rio Peruhype, in southeastern Brazil. Here is -named for 

 the first time the large black-eared opossum of southern 

 Brazil, to which both these names relate. 



In 1841 Lund (Kongl. Dansk. Vidensk. Selsk. Afhandl., 

 VIII, 1841, p. 236) described the azara type of opossum 

 occurring at Lagoa Santa as Didelphis albiventris, and a year 

 later Wagner (Arch. f. Naturg. 1842, i, 358) renamed the 

 same animal, from practically the same region, Didelphys 

 pcecilotis, which latter name has been generally taken instead 

 of Lund's, especially by German writers. In 1844 Schinz (Syn. 

 Mamm., 1844, p. 504), based the name Didelphys pcecilonota on 

 Rio Grande do Sul specimens, while Ihering has recently given 

 the name Didelphys lechei to the dark phase of the azara type 

 from the same region, and the name Didelphys koseritzi to the 

 dark phase of the aurita type of the same region. 



In 1900 I described (this Bulletin, XIII, pp. 192, 193) 

 two subspecies of the marsupialis group from, respectively, 

 eastern and western Colombia, under the names D. karkino- 

 phaga colombica and D. k. caucce; and also (/. c., p. 191) a 

 black form of the D. azarce (= paraguayensis} group, from 

 southeastern Peru, under the name Didelphis pernigra. At 

 this time I had not previously seen specimens of the D. 

 azarcz group, and was hence strongly impressed with its dis- 

 tinctness from any of the forms of Didelphis then known to 

 me. I was therefore greatly surprised, a year later, to find 

 it only a form of the so-called D. azarce. 



SPECIES AND SUBSPECIES OF DIDELPHIS. 

 The South American forms of Didelphis are separable 



1 See op. cit.,, footnote to p. 27, and the text, pp. 30 and 31. 



