MUSEUM OF COMPARATIVE ZOOLOGY. 185 



DIDELPHIDJE. 



35. Didelphys virginiana Shaw. Opossum. 



Didelphys viryiniana Shaw, Gen.Zo.il., I, 473, pi. cvii, 1800. — Desmar est, 

 Harlan, Temjiinck, Waterhouse, Baird, and most other authors. 



? " Didelphys marsupialis Schreb., Saugeth., Ill, pi. cxlv, 1778." 



Didelphys califomica Bennett, Proc. Lond. Zool. Soc, I, 40, 1833. — Also 

 Wagxer, Waterhouse, Aid. & Bach, (from Bennett). — Baird, Mam. 

 N. Am., 233, 1857. — Baird, U. S. & Mex. Bound. Surv. Rep., II, Zool., 

 32, 1859. 



Didelphys breviceps Bennett, Proc. Lond. Zool. Soc, I, 40, 1833. — Water- 

 house, Nat. Hist. .Mam , I, 477, 1846 (from Bennett '<.). — Aid. & Bai ii., 

 Quad. X. Am.; Ill, 330, 1S51 (from Bennett). 



Didelphys pruinosus Wagner, Wiegmann's Archiv, 1842, 358. — Water- 

 house, Nat. Hist. Mam., I, 477, 1846, (from Wagner). 



Abundant. 



This species is quite variable in its color-markings, and remarkably so 

 in many other features, especially in the length and size of the nose, and 

 in the size and proportions of the skull, even in specimens from the same 

 locality.* Slight and quite inconstant differences also occur between ex- 

 amples from the Southern States, Texas, Mexico, and California. It 

 would, in fact, be quite unusual if specimens of any species ranging so 

 widely should not be found to differ somewhat at localities so widely sepa- 

 rated. Two supposed species of North American Didelphys described 

 by Mr. Bennett, as cited above, have been quoted by numerous other 

 authors, and by them currently adopted, without apparently an exam- 

 ination of their merits. Professor Baird. rejecting one of them, has en- 

 deavored to separate the opossums occurring west of the Mississippi valley 

 from those living farther eastward, designating the western one as D. cali- 

 fomica. The distinctions claimed are somewhat similar to those urged as 

 distinguishing the so-called Procyon Hernandezii of the western half of 

 the continent from the /'. hilar of the Atlantic States. They are equally 

 slight and unsatisfactory, and at most mark but a geographical race, so 

 intimately allied to and intergrading with the better-known eastern form 

 that the point at which the one supplants the other is thus far undeter- 

 mined. The Didelphys breviceps of Bennett was founded on a single 

 specimen from California, which differed from the so-called D. califomica 

 only in having a relatively shorter head. 



* Since writing the above I have been incidentally informed by Dr. Cones that, in 

 preparing his memoir on the anatomy of Didelphys viryiniana (now publishing in the 

 Mem. of the Bost. Sue. Nat. Ili-t., Vol. 11, l't. I), he had occasion to examine a large 

 number of specimen-, ami that he found the variation in size and proportions to 

 amount to nearly twenty per cent. 



