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



and accurate, but is known to have been based on specimens 

 brought alive to England from Virginia. Besides this, there is 

 no question of the applicability of his description and figures to 

 this animal. On the other hand Mr. Thomas (/. <:., p. 144) claims 

 that Seba's account, cited also by Linnaeus and having precedence 

 in the order of citation, is also identifiable and relates almost be- 

 yond question to the large Opossum of Guiana and northeastern 

 South America, later named Didelphis karkinophaga by Zimmer- 

 mann. Linnaeus's D. marsupialis, as every one admits, was in- 

 tricately composite, including all of the then known forms of the 

 restricted genus Didelphis from both North America (including 

 Mexico) and South America. Unfortunately the first form of 

 the group to receive a new name was the Guiana species, as 

 above stated. The next to receive a name was the Virginia 

 Opossum, called Didelphis virginiana by Kerr in 1792. We have 

 still left of the Linnaean references the Tlacuatzin of Hernandez, 

 which undoubtedly relates to the form of Didelphis occurring in 

 Mexico. It has, therefore, seemed best to restrict^, marsupialis 

 to the large Mexican Opossum, as suggested by Rehn (/. c. p. 

 149), retaining Z>. karkinophaga as the specific designation of the 

 large Opossums of northeastern South America, and D. virgin- 

 iana Kerr for the Opossums of the eastern United States, this 

 course being not only warrantable, but scarcely disturbing the 

 current nomenclature of the group. (Cf. also postea, p. 169.) 



Kerr's name Didelphis virginiana was fortunately based on the 

 " Virginian Opossum " of Pennant's ' History of Quadrupeds ' 

 and not on that of his ' Synopsis of Quadrupeds,' as in the latter 

 case it would have been a pure synonym of D. marsupialis Linn. 

 In the ' Quadrupeds ' he so far modified the description first 

 given in the ' Synopsis ' as to make it not only strictly applicable 

 to the Virginia Opossum, as regards coloration and the relative 

 length of the tail, but he substituted a copy of Tyson's excel- 

 lent plate of this animal for the very " indifferent " one in the 

 ' Synopsis,' which represents a dark-headed, long-tailed South 

 American form. There is, therefore, no ground for questioning 

 the availability of Kerr's name, who simply paraphrased Pennant, 

 even to his erroneous statement of its distribution. 



Relationships. D. virginiana merges gradually into D. v. pigra 

 of the coast of Georgia, the Florida Peninsula, and the Gulf 



