Alexandra Days' ''Carl'' -- We talk to the author of the popular series of picture books about a baby-sitting canine

It’s not the kind of place you’d expect to find a 50-year-old woman who illustrates children’s books and wears her hair swept into a schoolmarmish knot. But here is Alexandra Day, south of the border in a Tijuana, Mexico, jai alai palace.

”We need your picks on this one,” her husband, Harold, 58, tells her as he prepares to make a bet. Dressed in a handmade silk and velveteen ensemble, Day looks more like she’s absorbing a sermon at her local Episcopal church back home in San Diego than sizing up fleet athletes with curved baskets strapped to their arms. Day deduces that players four and five will win. And they do — just about the time a waiter delivers her drink, a sludgy Kahlua concoction known as a Pemex Oil.

Alexandra Day has a knack for surprising juxtapositions. In fact, she’s famous for it: She’s the creator of a fierce-looking rottweiler named Carl who gently tends an infant in a series of children’s books that began in 1985, when Day’s family-owned Green Tiger Press published Good Dog, Carl. The series, which features very few words and lots of vivid pictures, has continued with Carl Goes Shopping and Carl’s Christmas and has sold close to 1 million copies. In 1990, Carl’s Christmas even knocked Judith Krantz out of the No. 4 position on the New York Times hardcover best-seller list.

Now comes Carl’s Afternoon in the Park. Farrar, Straus & Giroux has set a first printing of 400,000 copies of the new pictorial tale of Carl’s romp in San Diego’s Balboa Park. The publisher also is reissuing two earlier titles, so that by the end of the year there will be a total of 2 million Carl books in print. Columbia Pictures is developing a live-action movie, Carl’s Big Adventure, produced by Robert Lawrence (A Kiss Before Dying) and written by Jim Cox (The Rescuers Down Under).

While Carl has been wagging his way onto best-seller lists, the woman who created him has been hiding behind a pseudonym. Alexandra Day is really Sandra Darling-something she didn’t tell even the publishers who bought her work (including Paddy’s Pay-Day and Frank and Ernest) after Green Tiger Press was sold in 1986. Darling simply pretended to be Day’s agent. The pseu-donym ploy protected Day from having to squeeze publicity activities into already overstuffed hours.

Day presides over a pinkish, Spanish-style home near Balboa Park that rattles with the comings and goings of the Darlings’ seven children, ages 17 to 28. She dotes on her old-fashioned roses, does her share of the family’s vegetarian cooking, and sews all her own clothing from vintage patterns. (For many years, she wore nothing but long skirts because she loved the potential of all those yards of fabric.) And now that she has been revealed and has resigned herself to giving interviews, Day simply weaves them into her everyday whirl of writing checks for the kids, changing light bulbs, and stepping around the playful tussles of the family dogs — Arambarri, a rottweiler named after a favorite Basque jai alai player, and Sprocket, an Irish terrier.

Day dreamed up Carl from her experiences at home and at work in various family businesses. In 1970, the Darlings, who owned secondhand-book stores in San Diego, founded Green Tiger Press to publish postcard reproductions of illustrations culled from the antique children’s books that the family collects by the thousands. Their design studio, the Blue Lantern, has room after room of prized volumes by Arthur Rackham, Lothar Meggendorfer, and L. Frank Baum. ”When it comes to children’s books,” Harold Darling says, ”the bulk of excellence lies in the past.”

The Darlings put that excellence to work for them. In 1972, Green Tiger published its first book, All Mirrors Are Magic Mirrors, a rumination on children’s literature written by Harold and illustrated with antique drawings. It sold 50,000 copies by mail order, and the Darlings knew they had to expand. Their staff eventually grew to 35 people, including their kids, and Green Tiger even started publishing books by such contemporary artists as Cooper Edens (Helping the Flowers). Day, whose grandfather, father, and uncle were painters, took inspiration from her favorite old-world artists and began illustrating books of her own.

To find antique-book treasures, the entire family has repeatedly traipsed across Europe. ”I remember traveling with whole suitcases full of Pampers,” Day recalls of those forays. It was on one such trip to Zurich in 1984 that the Darlings chanced upon an 1860s German broadsheet titled Der Brave Karo, about a cartoon canine that charmingly cares for a baby whose mother had stepped out on an errand. Later, Day remembered the helpful poodle-type pooch but misremembered his name as Carl. Which is why she didn’t create a book called Good Dog, Karo.

For Day, there was only one woofer with the charm and good nature to be the real-life incarnation of Carl. She posed the family’s beloved pet, an affable rottweiler named Toby. Day has never been concerned about the breed’s fearsome reputation, explaining that ”it comes from rottweilers’ having a great desire to please their owners. If an owner wants violence, he’ll get it.” All the Darlings demanded from Toby was affection, and in return he was so gentle that Day didn’t hestitate to let her only grand-daughter, Madeline, model as Carl’s infant charge. The warmth Day put into her realistically rendered oil paintings has earned the books so much adoration that it’s not farfetched to speculate that Carl is partly responsible for boosting rottweilers, last year for the first time ever, into the top five of the American Kennel Club’s most-popular-breeds list.

Sadly, though, the family’s own ”Carl” died two years ago of old age. ”Everybody cried for a week, especially me,” Day says as she sips a cup of tea in her garden. ”And then I said to (my youngest son), ‘Let’s just go look at some puppies, just shop around.’ Well, of course, we bought the first one.”

That first one, Arambarri, looks up at her as she speaks. She rubs his head and talks about painting him as a puppy in Carl’s Afternoon in the Park. And even though he’s all grown up and Carl-size now, Day says she’ll never use Arambarri as a model for that good dog. ”Carl is always Toby,” she says with a wistful resolve. ”Always will be.”