Vol. 86, No. 33, pp. 391-402 14 December 1973 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON ANATOMICAL AND NOMENCLATURAL NOTES ON OPOSSUMS By Ronald H. Pine* Smithsonian Institution, Washington, D.C. 20560 From the time that specimens of different species of didel-phids became available to zoologists there has been confusion concerning which names to apply to the various genera and species. Uncertainty in regard to the presence or absence of a pouch in the different forms still persists also. This paper attempts to clear up much of this confusion. My investigations as outlined below show that the brown four-eyed opossum (currently called Metachirus nudicaudatus) totally lacks a pouch. Other characters of this species are pale-colored spots above the eyes, a basically reddish-brown colora-tion dorsally and little extension of fur onto the base of the tail. The gray and black four-eyed opossums (now called Thi-lander opossum and Philander mcilhennyi respectively ) possess fully developed pouches, also have pale spots above the eyes, have basically gray or blackish coloration dorsally and show considerable extension of fur onto the base of the tail. The generic epithet Philander Tiedemann will be shown to apply to the brown four-eyed opossum. This makes Meta-chirops Matschie the proper generic epithet for the gray and black four-eyed opossums. Seba (1734) described and figured opossums designated Philander, Opassum, sive Carigueja, Brasiliensis; mas and Phi-lander, Americanus, seu Carigueja, cum catulis, saccum ventris intrantihus; foemina. The description of the male animal reveals that the opossum in question has light tawny spots above the eyes and that fur of this color also covers the area * Present address: George Williams College, 555 Thirty-First Street, Downers Grove, Illinois 60515 33— Proc. Biol. Soc. Wash., Vol. 86, 1973 (391)
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