MOST OF A Reader's Guide to Fantasy consists of a bio-bibliography of fantasy writers -- from Lynn Abbey and Richard Adams through Cabell, Lovecraft, Machen and Morris to Chelsea Quinn Yarbro and Roger Zelazny. Each entry briefly recounts its author's career or influence and then describes his most famous books. I say describes because these encyclopedists are properly careful not to give away too much of any story.

After this opening section, the handbook lists the component titles in various fantasy series -- all the Oz books, all the Fafhrd and Grey Mouser collections. A thematic arrangement comes next: In books grouped under the rubric There and Back Again "someone from our world ventures, falls, or is abducted into another, more magical world." Beyond the Fields We Know includes tales which "take place entirely in magic worlds, with no concrete links to our own time and place."

Other sections of this guide list the 30 or so most important fantasy works -- what the authors call "the seven-league shelf" -- and the winners of various literary awards. A final chapter outlines the history of modern fantasy.

This is a good and useful introduction to an under-appreciated literary genre, and even better than its predecessor, A Reader's Guide to Science Fiction . At the very least it will provoke a few observations.

For instance, among the preferred backgrounds for fantasy is that of the traveling circus or carnival, Charles Finney's The Circus of Dr. Lao and Ray Bradbury's Something Wicked This Way Comes being especially notable. In its very essence, the circus is an interruption of the unreal into the evderyday; one expects the unexpected to occur there. So what better locale for the truly strange, mysterious and horrible?

Not unexpectedly, swords continue to flash in twilit worlds of mist and magic. Besides Robert E. Howard's Conan the Barbarian, one may encounter his mighty-thewed alliterative cousins Kull, Kane, Kothar, and Kyrik, or even the beautiful woman warrior Jirel of Joiry (whose castle is built on an entrance to hell).

At the turn of the century there seems to have been an obsessive fascination with Pan. Arthur Machen's The Great God Pan is only the best known among a group that includes tales by Algernon Blackwood, E.M. Forster, Oliver Onions, and Lord Dunsany. Did Pan embody some sense of release felt after the strait-laced Victorian era? Did the young shock their Apollonian elders by seeming to cast off gentlemanly and ladylike comportment for Dionysiac and lascivious abandon?

Sometimes just the outline of a story can generate reveries: One of Edward Eager's Half-Magic novels employs "the wonderful idea of a mysterious book checked out of the library that both chronicled the magic adventure as it happened and caused it to happen." In Le Fanu's pre-Dracula vampire story Carmilla , "the beautiful and immortan vampire, Carmilla, not only wishes the blood of the heroine, but approaches her on emotional levels, also, to the extent of giving the story strongly erotic lesbian overtones." Pan would approve.

But the siren-call of fantasy tales starts with their titles: The King of Elfland's Daughter, The October Country, The Black God's Shadow, The Last Unicorn, Till We Have Faces, The House onthe Borderland, The King in Yellow, The Wind in the Willows, All Hallow's Even, The Ship of Ishtar, The Wizard of Oz . Who could, or would, resist such books?