LATELY, IT SEEMS, every sf publisher is looking for the next big sf novel, the next fantasy trilogy. Meanwhile, quietly, for love, for money, for some reason, short stroies, novelettes and novellas keep being written and published in the genre magazines, story collections and anthologies. A very mixed bag this time, then -- two story collections and two anthologies -- so one can see what has been done and is being done in the short forms beneath all the hoopla and hype. (And in one case, what's being done to a writer by it.)

The Best of Thomas N. Scortia, edited by George Zebrowski (Doubleday, $11.95) is just what it says. Scortia has been a writer largely ignored within the field (though praised by the critics). The collection contains 11 stories and an essay, running story commentary and chunks of biography by Scortia, an introduction by Frank Herbert and an afterword by Robert Lowndes.

The stories cover two full decades (1954-1973) and range in quality from the medium-well to the wonderful. The two most powerful are at opposite ends of the book and of the author's career. The later novelette "The Weariest River" (1973) explores the frightening theme of immortality without the benefit of anti-aging technology: a prolonged life span in which the mind and body gradually fall apart. The story is set in a well-thought-out world, and a nasty one. Everybody in this world is a have-not; those who can't afford the treatment live and die, those who can just live and can't die. The tone and images from the story are haunting.

Back in 1956 Scortia wrote "The Shores of Night," a novella of mankind's leap from the solar system to the stars, and of the cost in human lives and its terrible toll in other ways on the direct participants. It is by turns chilling, awkward, evocative and overwritten. Even at its worst it explored areas, motivations and psychologies most writers of the time would not touch. It was a once-in-a-lifetime kind of story most writers would give half their careers for. It happened to Scortia only two years after he sold his first story.

As the author himself says, "The result is very much a young man's story. It has so many personal elements in it that . . . it remains painful to read. That is a Scortia that no longer exists, and, warts and innocence and all, I miss him."

The running biography introduces us to a writer much too ignored in this sometimes frustrating field.

Some writers in the genre have been accused of not having all the lights on their marquees. Samuel R. Delany, on the other hand, is charged with having so many lights on in his that what is spelled out there is sometimes lost in the brilliance and glare.

Delany, who surfaced in the '60s, is the award-winning author of brilliant shorts ("Aye, and Gomorrah," "Drift-glass") and novels (The Einstein Intersection, Babel-17 ) and of the long self-indulgent critical failure, Dhalgren.

His latest, Distant Stars (Bantam Books, $8.95), is in that most inappropriate of packages, the heavily illustrated trade paperback. The format recalls that of the Whitman Big Little Books of the '30s and '40s, only slicker.

For his money the reader gets six stories (including the Hugo and Nebula-winning "Time Considered as a Helix of Semi-Precious Stones"), the short novel "Empire Star," something Bantam calls "a fascinating new essay" (which is only an introduction) and, HAL help us, "the first computer-enhanced artwork created for a science fiction book." (To me, it looks like the artist was sloppy when doing wash-screening overlays.)

Delany is a wordsmith, a craftsman who creates images that are by turns shocking and full of wonder. His best works make their own pictures. He certainly doesn't need this kind of package, or this kind of hype from his publisher.

The stories range from award-winner to throwaway (though the worst that can be said of his stories, like "We in some Strange Power's Employ, Move on a Rigorous Line," included here, is that they don't work ). A couple of pieces of major Delany, an okay story, some trivialities and lots of Quaker Puffed Air between the words. Wait for the regular paperback, rip out all the pictures and then read the book. You'll save yourself lots of trouble.

Berkley Showcase Volume 4, edited by Victoria Schochet and John Silbersack (Berkley Books, $2.25), is the best of the series so far.

Begun as an in-house anthology (like Lester del Rey's Stellar series and Ace's Destinies ), it was to be published three times a year, but is now on an annual schedule. As with the others, the first few volumes were more uneven than, say, the average issue of the average sf magazine. Berkley Showcase, in particular, gave the feeling of being edited during the breaks of a rousing game of Fruit-Basket-Turn-Over.

The editors seem to have dug in and found all the good stuff they have lying around and put it in this one volume, rather than scattering it throughout a couple of books.

Not that all the stories are great, or work as stories (a nasty problem with younger writers). Doris Vallejo's "Seduction" is a burned-out vampire version of the Cupid and Psyche myth. Fine writing, but not much more. Alan Ryan's "Margaret Dead, Margaret Alive" is narrated in future tense (try that on your friends) and reads like a dream in the subjunctive case. It might have been wonderful but the story is slight and the distancing effect gets in the way. R. A. Lafferty, the Tulsa madman, offers a history of stained-glass windows you never knew was there; minor but full of mind-croggling images tossed off like so much sawdust from a mill. Jack Dann's "Fairy Tale" is a chockablock mixture of Jewish Catskill comedian/Irish leprechaun/Night in Mab's Hill craziness which bounces around in a mixture that just doesn't work for me.

In the high-middle range is "Blue Apes" by Phyllis Gotlieb, a story about a colony planet's possible salvation snatched away by the way things are back in the bureaucracy. It is told with imagery and insight. "Air Kwatz" by Ronald Anthony Cross is a bit of pseudo-Zen/hippie-dippie Cloud Cuckoo Land stuff. Yet this one almost works on a couple of levels. Then it just ends. Pat Cadigan's "The Pathosfinder" introduces new psychological technology like neurosis-peddling, and delves into the creative psyche, sometimes with insight and sometimes not. "Younggold" by Kevin O'Donnell Jr. is part of a novel -- it has one of the most remarkable images of the last few years in it -- but being a novel excerpt just ends. And beause of the purity of that image in the excerpt, some of the writing around it seems flat.

Which leads us to the book's two killers. "Alternate 51: Bliss" by Robert Thurston is an alternate world story like you've never seen before. Dreyer, the protagonist, is checking out his 51st alternate world for the government, all very business-like: the world Bliss is not especially interesting. But Thurston uses Bliss, and other worlds, as a sounding board to show some of the wonders and possibilities of this one, with immediacy and quietness.

Conni Willis' "Distress Call" seems at first an uneasy mix of images and metaphors: the fading of a ghost and the sinking of a ship. But it is told with conviction and it is chilling. The ending is all wrong, but this is one of those flawed masterpieces (like Scortia's "The Shores of Night") which comes along all too rarely. You will not be able to think of ghosts, or sinking ships, in quite the same way again.

Rounding out the volume are two poems by Marge Piercy and an interview with Elizabeth A. Lynn by Vonda McIntyre. Lynn talks of her writing methods, support and encouragement from friends, and where her work is going. Informative and not showy.

I hope the editors continue on the same path they've started here. They can't go wrong if they do.

Which brings us to one of the two surviving grandaddies of the original anthologies, Universe 11, edited by Terry Carr (Doubleday, $9.95). Started in 1970, this series moved from Ace to Random House to Doubleday, and somehow Carr has managed to keep a yearly schedule and never falter in matters of literary taste.

Not that Universe 11 will be for everybody. There's a particularly bleak and cool piece by Carter Scholz ("In Reticulum"), Kim Stanley Robinson's story about what the loss of even one city means to culture ("Venice Drowned"), and a strange genetic engineering story by Ian Watson. Carol Emshwiller tells of alien invasion in her particular peculiar voice, and Nancy Kress and Josephine Saxton have stories here.

There are three standouts. Michael Swanwick's "Mummer Kiss" takes place in a future where Three Mile Island did melt down, set in a radioactive area called The Drift. The story is gripping up until the end (that old last-pages problem again) and them becomes predictable. Swanwick can evoke stange futures better than anyone who has arrived on the scene lately.

William Gibson contributes "The Gernsback Continuum" in which the protagonist glimpses the World of Tomorrow as predicted in all those old Popular Science magazines of the 1930s. (But Flying Wings have always been one of my soft spots.)

Michael Bishop's "The quickening" is an understated and beautiful novelette of the dismantling of the world after all humans have been pulled from their countries and cultures and put down in some other. This is a catastrophe story on several levels -- cultural, personal, social. It is also an uplifting one.

The Bishop, the Gibson and the Swanwick (flawed as it is) are worth the price of the book.