Here are a few references:

Metachirus nudicaudatus (brown four-eyed opossum)
Philander opossum (grey four-eyed opossum)
http://www.uni-hohenheim.de/~bahagish/Didelphoidea.htm

And here, together with their local names, as well as their latin names:

Cica comun Brown Four- eyed Opossum Metachirus nudicaudatus
Comadreja gris Grey Four-eyed Opossum Philander opossum
http://www.yacutinga.com/mammals_and_birds.htm

Another interesting site about opossums gives:

"The gray four-eyed opossum (Philander opossum) and the brown four-eyed, or rat-tailed, opossum (Metachirus
nudicaudatus) have a pair of large whitish spots over the eyes. Both are found in Central and South America; they have large
heads and long tails, and the latter species is pouchless."
http://jurique.agava.ru/opossinf.htm

"Four-eyed opossum Philander nudicadatus"
http://www.zoologicalfauna.com/mammals/mammals_list.htm
(note: I think that "nudicadatus" is a mistake and should read "nudicaudatus". )

"Philander nudicaudatus Four-eyed oppossum"
http://www.guyanawildlife.com/default.asp?cat=4¤tpage=...

The French don't seem to have a common name for these marsupials, and just use the latin name:

" Par exemple, les sarigues
Didelphis marsupialis provenant de 5 localités distantes ne diffèrent en moyenne que par 0.3% de différences
génétiques, alors que, pour ces mêmes localités, le marsupial Metachirus nudicaudatus renferme des haplotypes dont
la divergence moyenne est au moins cinq fois supérieure"
http://kourou.cirad.fr/silvolab/html/projet_chasse.html

"Structuration spatiale et stratégies de reproduction chez deux marsupiaux Didelphidés de Guyane (Didelphis marsupiulis et Philander opossum) : relation avec la structuration génétique des
populations"
http://www.univ-paris13.fr/Menugauche/Evenements/thes9900.ht...

or (talking about a virus):
"Isolé par le Laboratoire de Virologie de Belem, Para (Brésil), à partir d'un broyat d'organes de Philander opossum"
http://www.pasteur.fr/recherche/banques/CRORA/bibref/br01720...

Unfortunately, I cannot find any instance in French of the expression "philander nudicaudatus", which seems to include both kinds, grey and brown.

Hope this helps anyway.