squirrel or rat in attic?

[Paul Wakfer]

My friend Eddie trapped a four inch rodent in his attic. He and I cannot

> recognize what kind of rodent it is. I thought at first it was a mouse > or a rat, but its feather-like tail makes me doubt this.

it looks like an opossum

[Bert Byfield]

A possum has a naked tail like a rat. A "feather-like" tail sounds like a squirrel.

[Paul Wakfer]

Bert Byfield wrote

well, since I live near the OP's friend "Eddie", I can tell you we have some unusual looking opossums of the not-normal-tail variety.. thus my guess is still an opossum

[DrLith]

Does it have very large, black eyes and a furry flap of skin between the front and rear legs? Possibly a flying squirrel! (If you're in the U.S., there's a couple of species that are less rare in urban areas than you might imagine.)

They're smaller and "mousier" looking that regular squirrels, and have a tail that could, indeed, be describes as feather-like. Here's a link to some info on the southern variety, but the northern variety looks very similar.