A DASH OF THIS, a pinch of that- from the short-story stew of the anthologist Geoff Hancock comes Fire Beneath the Cauldron (Thistledown, 320 pages, $18.50 paper), a rich, strange, and if not always consistent, certainly surprising collection of Canadian short fiction. Hancock, who states in his rambling introduction that his objective is to go deep "into the depths of the narrative, perhaps to the structure of the human psyche," includes 22 stories from such contemporaries as Brian Fawcett, Douglas Glover, Janice Kulyk Keefer, and Marlene Nourbese Philip. And while the whole doesn`t quite measure up to the anthologist`s lofty intentions, the parts certainly demonstrate Hancock`s exceptional taste for modern short fiction. There is a powerful diversity of voice here, as might be expected from writers whose styles range from the magic realism of Ernest Hekkanen to the textual parody of Bill Gaston. Only half of the stories deal directly with matters of the psyche and spirit - most notably Carol Shields`s "Dolls, Dolls, Dolls, Dolls" and Dionne Brand`s "Blossom, Priestess of Oya, Goddess of Winds, Storms and Waterfalls." While the rest of the contributions never stray far from this thematic range (after all, what story doesn`t deal with psychospiritual concerns?), there are a few that seem to have been included for no other reason than that they tell a good story. Which, of course, is just fine. Bill Gaston`s "The Forest Path to Malcolm`s," for instance, is a hilarious, subversive send-up of the legend of Malcolm Lowry that would brighten any collection. Hancock`s editorial attempts to relate it to the depths of the human psyche, however, are an unnecessary intrusion on an otherwise exceptional anthology.