1. DIDELPHTS. 329 



variable in its general coloration ; but distinguishable by , tbe 

 prominence and sharp definition of the darker marks on the face, 

 these forming strongly contrasted black stripes on a white ground, 

 one running through each eye, and a median one passing from 

 between the eyes backwards on to the crown and back of the neck. 

 Specimens with these markings are generally smaller in size, and 

 have, as a rule, white or parti-coloured ears, more hairy tails, and 

 smaller teeth than the ordinary form, but no one of these characters 

 is entirely constant. 



Dimensions. Skull, see p. 341. 



Sah. The countries bordering the Amazonian Eegion on the west 

 and south : Colombia, Ecuador, Peru, Bolivia, Chili, Paraguay, and 

 S. BrazU. 



Type not in existence. 



a. Imm. sk., (J. Santa F6 de Bogota, Purchased. 



Colombia. 

 Bolivia. Mr. T. Bridges [0.]. ' 



i Yg. St. I 

 • [Skull, f 



e. Yg. sk. Bolivia. Mr. T. Bridges [0.1. 



d. Ad. skull. Bolivia. Mr. T. Bridges [0.]. 



e,f. Imm. St., ^ 5 . ChUi. Purchased. 



ff, h. Imm. & yg. al., S ■ Taquara, Rio Grande Dr. H. von Ihering [0.]. 



do Sul. 



j-m. Skulls. Taquara. Dr. H. von Ihering [C], 

 n. Skeleton. 



II. Subgenus METACHIEUS. ^ 



Type. 



Metachirus, Burm. Thiere Bras. i. p. 135 (1854) .... D. nudicaudata. 



Size medium. Proportions of hind toes as in the subgenus 

 Didel/phys, i. e. with the three central toes subequal, all much 

 longer than the fifth. Pouch either well developed or rudimentary. 

 Fur short, straight, of one sort only, without longer bristles 

 intermixed. 



Shull with a very small narrow brain-case, its most constricted 

 point some distance behind the postorbital processes. Temporal 

 crests and ridges generally weU developed. Teeth as in DidelpJiys. 



2. Didelphys opossum. 



Philander opossum seu Carigueja, Seba, Thesanr. i. pp. 56 & 57, 



pi. xxxvi. figs. 1-3 (animal) (1734). 

 Didelphys opossum, lAnn. 8yst. iVai.(lO) i. p. 65 (1760) ; Mull. 



Linn. Natws. i. p. 292 (1773) ; Schreb. Sdvg. iii. p. 587, pis. cxlvi. 



A & B (animal) (1778) ; Zimm. Geogr. Gesck. ii. p. 222 (1780) ; 



Bodd. Elench. Anim. i. p. 77 (1785); Gmel. lAnn. Syst. Nat. i. 



p. 105 (1785) ; Kerr, Linn. An. K. p. 192 (1792) ; Brnind. Zool. 



Beytr. i. p. 345 (1792) ; G. Cuv. Tabl. EUm. p. 124 (1798) ; 



Laeip. MSm. Inst. iii. p. 491 (1801) : JE. Geoff. Cat. Mus. p. 141 



