1 90 1 .] Allen, Opossums of the Genus Didelphis. 165 



Coast, diverging more perceptibly in Florida from the northern 

 form, and reaching its extreme differentiation in the southern 

 half of the Peninsula. South Florida specimens are, as already 

 said, readily distinguished from New York and New Jersey speci- 

 mens by strongly marked color differences, and perhaps by a 

 slight average increase in the length of the tail. 



In the Lower Rio Grande region of southern Texas there is 

 apparently a rather abrupt transition from the D. virginiana type 

 to the dichromatic form of the Lower Rio Grande region, both in 

 coloration and in the. relative length of the tail. Nevertheless it 

 evidently diverges from the typical northern toward the southern 

 animal near the southern border of its distribution in Texas. 



Didelphis virginiana pigra Bangs. 



Didelphis virginiana pigra BANGS, Proc. Boston Soc. Nat. Hist. XXVIII, 

 1898, 172. March, 1898. 



Type locality, "Oak Lodge, on the east peninsula, opposite Micco, Brevard 

 Co., Florida." 



Distribution. Florida, coast of Georgia, and Gulf Coast west to Texas. 



Darker, but in all other respects similar to D. virginiana. The underfur 

 has a much broader apical zone of black, the covering of white overhair is 

 generally much reduced, the blackish face markings are more pronounced, 

 the median extension of dusky on the head often extending as far forward 

 as the front of the eyes, and the anteorbital spot is much larger. The white 

 on the toes is much reduced, being often entirely absent on the hind toes, and 

 the white on the apical border of the ears is often reduced to a mere trace ; 

 on the other hand the black at the base of the tail often extends considerably 

 beyond the covered portion, particularly in South Florida examples, where there 

 is also a tendency to melanism. 



In measurements and proportions (see Table II of measurements) quite 

 similar to D. virginiana of the northern States. In a series of 4 specimens 

 from Kissimmee River, Fla., the ratio of tail length to length of head and body 

 is 74.5. 



Z>. virginiana pigra is not sharply or very strongly differentiated 

 from D. virginiana (typica), but South Florida and Louisiana 

 coast specimens are quite unlike the northern form through their 

 much darker general coloration, the increase in extent and dis- 

 tinctness of the facial markings, a tendency to a greater extension 

 of black on the base of the tail, and the reduction of white on the 

 toes and ears. 



Geographical Distribution. D. v. pigra may be considered as 



