160 Bulletin American Museum of Natural History. [Vol. XIV, 



SYNOPSIS OF SPECIES AND SUBSPECIES.* 



A. Posterior border of nasals forming a V-shaped point. 



a. Tail black only at extreme base ; generally less than two thirds the 



length of head and body (tail ratio about 70) D. virginiana. 



b. Tail black for basal third ; generally four fifths the length of head and 



body, or more (tail ratio about 90-95) D. marsupialis texensis. 



c. Tail black for basal one third to one half ; generally as long as head and 



body or longer (tail ratio about 100-110) D. richmondi. 



B. Posterior border of nasals obtusely truncated. Tail black for basal one 



third to one half, or more. 



a. Nasals very short and very obtuse posteriorly ; tail generally about nine 



tenths the length of the head and body (tail ratio about 85-95) 



D. marsupialis. 



b. Nasals much longer and less obtusely pointed posteriorly (tail ratio 95 



105) D. marsupialis tabascensis. 



Didelphis virginiana Kerr. 

 VIRGINIA OPOSSUM. 



Didelphis marsupialis LINN. Syst. Nat. ed. 10, 1758, 54. (In part only.) 



Virginian Opossum, PENNANT, Hist. Quad. 1781, 301, no. 181, pi. xxxiv. 

 (Excluding Mexican and South American references.) 



Didelphis virginiana KERR, An. King. 1792, no. 386, p. 193. (Based on 

 Pennant, as above.) 



Didelphis virginiana SHAW, Gen. Zool. I, pt. 2, 1800, 473. (Based exclu- 

 sively on the Virginia Opossum.) Also of most recent authors. 



Didelphis -woapink BARTON, Facts, Observations, and Conjectures relative to 

 the Generation of the Opossum of North America, 1806, 2. 



"Didelphis pilosissima and illinensium LINK," apud Gray, List Mamm. 

 Br. Mus. 1843, 100. (Cf. Thomas, Cat. Marsup. and Monotr. Br. Mus. 1888, 

 325, footnote.) 



Type locality, Virginia. 



Distribution. Eastern United States, south to the coast region of Georgia 

 and the Gulf States. 



Adult. Pelage of two kinds of hair, an outer long coat of rather coarse white 

 overhair, sufficiently abundant to give tone to the general coloration ; beneath 

 this a coat of long, thick, soft woolly underfur about 40 to 50 mm. long, on the 

 back, white (sometimes nearly pure snowy white in clean winter specimens, but 

 usually with a slightly yellowish cast) for four fifths of its length, the apical fifth 

 of the longer fibres of the underfur being blackish. The long white overhair 

 varies in abundance in different specimens and on different parts of the body, 

 being nearly obsolete on the ventral surface, longer on the back than on the sides, 

 and longest on the lower back and at the base of the tail, where it attains a length 

 of 60 to 80 mm. General color above mixed black and white, the blackish tips 



1 Didelphis nelsoni, sp. nov., is not included ; see postscript, p. 185. 



