In Virginia's horse country, the women who ride sidesaddle should not be called women. They are ladies.

They ride in long skirts and top hats, both legs positioned carefully on the left side of the horse, controlling and communicating with it almost entirely through balance. They often must carry a flask of sherry on the saddle and a small leather case containing a regulation sandwich -- no crusts. Those who can do it are elegant in appearance, graceful in performance.

"It's very much like being a princess," said Callie Fulmer of Lovettsville, a sidesaddle rider for the last five years.

There aren't many ladies left. The heyday of sidesaddle, originally ridden by women who considered it unseemly to ride astride, passed long ago, and membership in the country's two main sidesaddle associations is down to a few hundred.

But those who still "ride aside" are devoted to keeping the tradition alive, and many of them are on hand this week at the Upperville Colt and Horse Show, the oldest show in the country. The event, at the show grounds straddling Route 50 west of Middleburg, ends Sunday with Olympic-class riders competing in Grand Prix jumping. The sidesaddle classes -- some with jumps, some without -- are scheduled for Saturday.

The rules that govern sidesaddle classes are reminders of the days when horses were the best means of transportation and hunting was the most efficient way to grab a meal.

In the "under saddle" class -- walk, trot and canter -- riders wear formal hunt attire: the skirt (known as an apron), a jacket, vest, boots, a stock tie (which was useful for bandaging an injured horse if the need arose) and a top hat at least 41/2 inches tall. If the rider has a letter confirming membership in a recognized fox hunt, the vest may be of the hunt's official color.

Judges will measure the height of the hat; they will check the sherry; and they have been known to take a bite of the sandwich -- which, besides being crustless, must be made of white meat, hold the mayo.

One-quarter of a rider's score depends on the gear, as Rose Marie Bogley well remembers. Bogley, a longtime Upperville resident whose age will remain her business as befits a lady, began riding sidesaddle in the late 1960s, after her husband, Samuel, died in a fox hunting accident.

She, too, was an avid fox hunter, and about that time, the hunt's master said: "You're still young and pretty. Why don't you try sidesaddle?" She began riding aside and, she says, "beat all the young kids out there."

Her home, on a 400-acre estate, is a testament to that. Besides the oil paintings of horses that line the walls of the manor house, countless ribbons and more than 50 photographs of her at horse shows take up an entire room. The trophies are distributed among other rooms.

"That's me in Upperville. That's me at the Garden," she told a visitor recently, indicating her name in lights at Madison Square, just like Walt Frazier before her.

By the time Bogley took up the discipline -- about a century after the invention of the modern-day sidesaddle -- it had already fallen out of fashion. World War II had emboldened women to do whatever men could do, including riding astride. Its popularity has ebbed and flowed since then, but it has always remained outside the mainstream.

The U.S. Equestrian Federation has a sidesaddle division, but the American Quarter Horse Association, the largest breed organization in the world, does not. And some riders regard sidesaddle as awkward at best, kooky at worst.

Glenn Petty, executive director of the Virginia Thoroughbred Association, finds watching women ride sidesaddle akin to watching people bungee jump or sky dive.

"I just kind of look at it and think, 'I could really not do that,' " Petty said, adding, "It looks rather uncomfortable, and it doesn't look particularly safe, either."

Sidesaddle riders beg to differ. It is not only comfortable, they say, but also more secure, because the specially made saddles give them a firmer grip.

A brace known as a "leaping horn" curves out from the saddle and over the top of a rider's left leg to help keep her in the saddle. An "upright horn" curves out from the saddle under the rider's right knee for more stability.

The other day, Penny Denegre -- who, also ladylike, would say only that she is in her forties -- appeared perfectly comfortable sitting sidesaddle on a thoroughbred named Hero, even as he shifted into a brisk trot on her 100-acre Middleburg farm. Although Hero is in the early stages of training, he moved smoothly under her, which is the whole idea. A fidgety or distracted horse wouldn't impress the judges.

And because Denegre's legs were on the left, Hero's entire right side was fully exposed, showing off his graceful movement -- his extended form, his flexing muscles, his lively gait. He made it all look effortless.

For her own part, the rider said she was feeling pretty good. "It's exactly the way you feel when you get dressed for a ball," Denegre said.