270 Bulletin American Museum of Natural History. [Vol. XVI. 



Ihering's D. lechii was based on dark specimens from Sao 

 Paulo. 



The Chaco specimens are practically topotypes of Azara's 

 Micoure premier, Azara's headquarters when he wrote his 

 'Quadrupeds du Paraguay' having been Asuncion, from 

 which the Chaco localities are only about 50 to 70 miles 

 distant. Goya is about 200 miles to the southward. The 

 Chaco specimens are either wholly black, or have only a few 

 scattered white hairs, while none of the Goya series is 

 black. 



Respecting the relative proportion of specimens of the two 

 color phases, light and dark, it is of interest to note that 

 Hensel (/. c.) states that of 57 specimens (the sexes equally 

 represented), of which he noted the color, n were black, 45 

 white, and i intermediate; and that in a litter of 9 young 

 found in the pouch of a white female, one was black, two had 

 a few white hairs, and the rest were of the white phase. 

 This affords conclusive evidence, if any were needed, that 

 the dimorphism has no relation to sex or age. 



There is little doubt that Temminck's name, azarcz, properly 

 relates to this animal, which he identified with Azara's 

 Micoure* premier. 1 His description is pertinent to this in 

 every respect except one, and not at all to the black-eared 

 opossums of the marsupialis group. Throughout his des- 

 cription he reverses the color of the ears, as though writing 

 from memory rather than with the specimens before him; 

 describing them as yellowish at the base and all the rest 

 black ("le plus souvent jaunatres a la base seulement, et 

 noires sur tout le reste"). Owing to this error Wagner 

 (Abhandl. Akad. Wiss. Mtinchen, V, 1847 [1850], 127) re- 

 named Azara's Micoure premier D. leucotis, and applied the 

 name azarce to the black-eared species of southern Brazil, 

 which Wied had named D. aurita. While it may be held 

 that Temminck's name is clearly identified by his description 

 as being applicable, as he intended it to be, to the animal 

 described by Azara under the name Micoure' premier, it is 

 perhaps not an unmixed evil that an earlier name for the 



1 Cf. Thomas, Cat.fMarsup. and Monotr., 1888, p. 328, footnote. 



