<BLOCKQUOTE><I>"On the lawns and porches, and in the living rooms and backyards of my threescore years, there have been more dogs, written and drawn, real and imaginary, than I had guessed before I started this roundup."</I></BLOCKQUOTE><P>Here is James Thurber, arguably the greatest humorist of the twentieth century, on all things canine. In <i>The Dog Department,</i> Michael J. Rosen, a literary dogcatcher of sorts, has gathered together Thurber's best in show. Here we have the stylish prose and drawings from <i>Thurber's Dogs</i> (which connected the words "Thurber" and "Dog" as inseparably as "Bartlett" and "Quotation," as "Emily Post" and "Etiquette"), along with unpublished material from the Thurber archives, a great sheaf of uncollected cartoons, and two dozen "Talk of the Town" miniatures from <I>The New Yorker</i> &#8212; the consummate dog book from an artist of extraordinary pedigree. What other author can claim to have penned his own personal breed? The Thurber hound is a creature as unmistakabl