No.410] DIDELPHIS MARSUPIALIS LINNAEUS. 149 
According to the evidence set forth, the point is raised, — 
should Tyson’s reference be given precedence over that of 
Hernandez? 
Disregarding the dates of the references (that of Hernandez 
being forty-seven years older), we will proceed with the work 
by elimination. 
The opossum “from Virginia" was separated by Kerr in 
1792, while the southern Mexican animal, which, if it has 
been separated, can only be either californicus or breviceps 
Bennet, which were not described until 1833. The only other 
species of the genus which is found anywhere near the locality 
in question is D. aurita, which has not (to my knowledge) been 
recorded north of Guatemala. The elimination of Tyson’s 
reference by the D. virginiana Kerr leaves us only the 
reference of Hernandez as the base of Didelphis marsupialis 
Linnzeus. 
ACADEMY NATURAL SCIENCES, PHILADELPHIA. 
