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Show 1894.] DIDELPHYID^E O F S.E. BRAZIL. 459 Winge12, and Hensel3-it appears that, however many recognizable forms of the subgenus Didelphys there may ultimately be, all the Opossums obtained by myseif in the Orgaos Mountains are exclusively D. aurita, whether this be itself reckoned as " species " or " variety." This is distinctly the animal so well represented by Burmeister, plate iii. of his 'Erlauterungen.' And the determination becomes certain from the cranial views (Burmeister, pi. v. fig. 3, pi. vi. fig. 1) and the osteological details given by Hensel (tigs. 3, 6). Evidently it was not one single character, but a complexity of features, which engaged Winge not to drop D. albi-ventris as a remarkable and constant Campos-variety of D. marsupialis. The same complexity of features occurs to m e in regard to D. aurita of the forest coast-region of Eio de Janeiro 4; and I may now add that during a stay of more than ten years in this province, in the hot and low zones, as well as in the mountains of the Serra dos Orgaos, I have always met with exactly the same form among the hundreds of specimens 1 had occasion to see. Some of the specimens in m y collection agree exactly with Burmeister's plate iii., showing the same general reddish-brown colour of fur, with longer whitish or greyish piles on the whole back or at least on the posterior part. Others are more or less blackish, with longer piles or bristle-hairs of the same colour, the points of these piles being split, as a rule, into many branches, especially on the dorsal median line, and appearing dirty white. N o correlation with age, sex, or season could be discovered in regard to the presence or absence of the whitish piles, and I made exactly the same observation referred to by Hensel (p. 112). I took notes about the last twelve specimens I saw : seven of them had white bristle-hairs intermixed, while five were more or less blackish. Of these seven specimens four were adult males, one a young male, one an old female, and one a half-grown female. They were collected in August 1891, April 1892, February 1893, May 1893, and three in December 1893. The five blackish specimens were caught in October 1892, February, March, July, and August 1893, and three of them were males (old, medium, and young) ; two were females, both half-grown5. The face- 1 ' Jordfundene og unlevende Pungdyr (Marsupialia) fra Lagoa Santa, Minas Geraes, Brasiliens,' Kjobenhavn, 1893. 2 Lagoa Santa. Et Bid rag til den biologiske Plantegeografi af Egnens Vanning,' Kjobenhavn, 1892. (Lagoa Santa Egnens Hvirveldyr.) 3 " Beitrage zur Kenntniss der Saugethiere Siid-Brasiliens," Abhand. d. gonigl. Akad. d. Wissensch. Berlin, 1892. 4 It can be seen by Pelzeln's 'Brasiliscbe Saugethiere ' (Wien, 1883), p. 109 et seq., that Natterer also determined all bis specimens of large Didelphys, collected in the neighbourhood of Rio de Janeiro and the coast-region, as belonging to D. aurita. About six specimens collected in Sapitiba (district of Rio de Janeiro) Natterer noted on tbe label a sign of question, but Pelxeln adds the words:-" Diirfte wohl zu D. aurita zu reebnen sein, wahrend die ecbte D. cancrivora dem Norden Siid-Amerikas angehort." It is to be regretted that Pelzeln's work on Natterer's Brazilian Mammals is not provided with good illustrations, especially of the smaller Didelphyidaj and Rodents. 5 Hensel states that among 57 individuals of D. azarce he noted 11 black |