1902.] Allen, Opossums of the Genus Didelphis. 267 



Measurements. As shown in the subjoined table (p. 278), 3 adult 

 males from San Paulo measure: Total length, 778 mm. (745-806); 

 head and body, 417 (405-426); tail, 349 (340-380); hind foot, 58 

 (48-61); ear, 48 (46-50). Six adult females average somewhat less. 

 Skull: Total length, 7 males, 106 (96-109); basal length, 95.3 (94- 

 100); nasals, 50.4 (47-54.5); zygomatic breadth, 55.5 (52.5-60); 

 postorbital breadth, 23.4 (20-26.5); postorbital constriction, n (10- 

 12); occipital breadth, 31 (30-32); breadth at canines, 19.7 (17.5- 

 20.5); upper toothrow, 33 (31-36); molar series, 19 (18-20). 



Specimens examined: 



Brazil: Rio Rodeio, Serra do Mar, near Rio de Janeiro, i specimen; 

 Rio de Janeiro, i specimen; Cruziero, Sao Paulo, 8 specimens; Piquete", 

 Sao Paulo, 7 specimens; Taquara, Rio Grande do Sul, 4 specimens, 

 including paratypes of D. koseritzi Ihering; Rio Grande do Sul, 6 

 specimens. 



Total, 27 specimens, coll. British Museum. 



D. m. aurita of southern Brazil is smaller than true marsu- 

 pialis of northern Brazil, much darker in coloration, and 

 with much better-defined head markings. It more resembles 

 the dark forms of northern and northwestern South America, 

 but has the head markings more distinct and is very much 

 smaller. In exceptionally strongly marked specimens the 

 head markings sometimes approach in distinctness those of 

 D. paraguayensis, but in such cases the light markings are 

 deep buft'y instead of clear white, and the dark areas are 

 more brownish black and not nearly so sharply defined. 

 Authors, however, have sometimes failed to distinguish these 

 two very distinct forms, which seem to occur together over 

 quite a large area. 



Didelphis paraguayensis Oken. 



Carigueya brasiliensibus , MARCGRAVE, Bras. 1648, 222 (apud Lund, I.e.). 



Tai-ibi brasiliensibus, MARCGRAVE, Bras. 1648, 223. 



Micoure premier, ou Micoure proprement dit, AZARA, Quad. Parag. I r 

 1801, 244. 



Did\elphys} paraguayensis OKEN, Lehrb. der Naturg. Theil III, Abt, 

 ii, 1816, 1147. Based primarily on Azara (cf. antea, p. 251). 



Didelphis azarce TEMMINCK, Mon. Mamm., 2 Mon. 1825, 30. RENG- 

 GER, Naturg. Thiere Parag. 1830, 223. Grand Chaco and Provinces 

 of Entre-Rios and Banda Oriental. MARTIN, P. Z. S. 1834, 101, 

 anatomy. THOMAS, Ann. and Mag. Nat. Hist. (7) VIII, Dec. 

 1901, 536. Rio Jordao, southwestern Minas Geraes. 



