DIDELPHTID^. 281 



18890 a. I'ragment of the left ramus of a mandible, apparently 

 belonging to this species. All the cheek-teeth except pm. 1 

 are preserved ; the length of the space occupied by the 

 true molars being 0,0135. 



JBiBcIpi^pj; nutJkautlata, Geoffrey K 

 Syn. Didelphys myosura, Temminck 2, 

 Didelphys affinis-myosurce, Lund ^. 



Length of lower series of cheek-teeth in two recent examples 

 0,0i^3-0,022, and of the true molars 0,013; pm. 4 and p^^ are 

 subequal in height, and m. 4 is shorter than m. 3. 



It would be very difficult to distinguish this form in the fossil 

 state from D. qidca and D. ojjossum, which inhabit the same area ; 

 the urfdermentioned fossil is referred provisionally to D. nudicaudata 

 on account of Lund's reference of other specimens to that type 

 {D. affinis-myosurce). 



Hah. Brazil and Guiana. 



18890 b. The nearly entire left ramus of the mandible, showing all 

 the teeth except the incisors. The length of the cheek- 

 series is 0,0215, and that of the true molars 0,013. 



i0it»elp]^g£S ctiurca, Temminck \ 

 Length of series of lower cheek-teeth in a recent specimen 0,017, 

 and of the true molars 0,010 ; pm. 3 is taller than pi^^. 

 Hah. Brazil. 



18890 c. The greater part of the right ramus of the mandible, 

 showing all the teeth except the incisors. The length of 

 the series of cheek-teeth is 0,017, and that of the true 

 molars 0,0105. 



IBiUelpf)!)^ griisiea, Desmarest \ 



Syn. Didelphys incana^ Lund ^. 



Didelphys affinis-incan(B, Lund ''. 



Somewhat smaller than D. cinerea, the length of the lower 



1 Nouv. Diet. d'Hist. Nat. vol. ix. p. 424 (1817). 



^ Monogr. d. Mammalogie, vol. i. p. 38 (1827). 



3 K. Danske Vid. Selsk. Skr. vol. viii. p. 293 (1841). 



^ Monogr. de Mammalogie, vol. i. p. 46 (1827). 



s Diet. Sci. Nat. vol. xlvii. p. 393 (1827). 



6 K. Danske Vid. Selsk. Skr. vol. viii. p. 237 (1841). 



^ y/fid p. 293(1811). 



