If ursulav jumped off a cliff, would I?

There's this kids' book I remember only vaguely, not including the title.

It's about a mouse that leaves home and lives in a swamp with some frogs who have no longterm memory. She gives them names, one of which is Aloysius, and makes clothes for them. But once she goes away for a coupla days. When she gets back they've forgotten what the names she gave them are, which clothing items are shirts and which are pants, and who she is. Then their turtle friend comes along and says to her (in so many words), "But you knew they have no longterm memory."

The frogs call the mouse Mouse Mouse. When the turtle hasn't forgotten her like the frogs have, addressing her as Mouse Mouse, in her excitement and relief she calls him Turtle Turtle. (I guess he didn't have a name before she came along either. Only animals culturally anthropomorphic enough to wear clothes and live outside the forest name themselves.) Googling "mouse mouse" brings up lots of pages on computer accessories, and "turtle turtle" brought up some nature sites and an Amazon.com page for an unrelated children's book.

Can anyone tell me the name and/or author of this story? Thanks.

Tonight's Grey's Anatomy

( Spoiler )