When Michael Shwedick and his travelling road show set forth from their makeshift warehouse in Prince George's County, the cast of characters usually runs something like this:

Oliver Twist, a 35-pount South American boa constrictor, "He's strong enough to kill anyone here," Shwedick clamly tells audience with Oliver drapped around his neck. "But of course he'd never do it."

Ra Junior, a very active, 4-year-old American crocodile, with a mouth full of very sharp teeth. "Don't worry, he won't get away from me," Shwedick confidently assures a group of gaping school children as the crocodile thrashes and twists in his hands.

Samadant, a 10-foot-long, 60-pount Indian python.

Myra, a 31-year-old South American yellow-footed tortoise weighing 35 pounds.

Iggy, a South American green Iguana.

An assortment of rattlesnakers, cobras, water moccasins and cooperheads.

For more than two years, Shwedick has been touring schools and recereation centers throughout the Washington area with his travelling reptile show in an effort, he says, to teach "what reptiles are really like."

"There's nothing unpleasant about touching a snkae. They're really very soft," he says, inviting a group of children to handle one of his pythons or boa constrictors.

He estimates he has visited between 400 and 500 schools and another 200 recreation centers and day camps, most of them in the Washington area but some as far away as Connecticut.By now, his reptiles have been seen by tens of thousands of children and for next year, he has bookings as far ahead as April, at fees ranging up to $225.

"The children love him. We have to hold the school buses whenever he's here because they don't want to leave," says Wendy Emmett, a firstgrade teacher at Fairfax County's Green Acres school.

To get his show on the road, Shwedick, 24, has a collection of more than 100 reptiles to draw on, most of them in a makeshift warehouse off Branch Avenue just across the District line in Maryland.

These include 30 crocodiles, 25 lizards, 35 snakes and 15 turtles. Among the more notable are two 100-pount Nile crocodiles named Samson and Delilah, a 35-pound Indian monitor lizard, a Malaysin albino soft-shell turtle, several African and Asian cobras, two baby salt-water crocodiles, a 100-pound snapping turtle and a gila monster.

Feeding the collection presents some interesting problems in logisltic. For his lizards, Shwedick has 1,000 grasshoppers flown in each week from a grasshopper supply house in Louisiana at a cost of $13.29 COD. About twice a year he drives to Pittsburg where he buys a truckload of dead mice and rats from a laboratory supply house at prices ranging from $25 to $50 per hundred, depending on the supply. They go into the freezer until it's time to feed some of the snakes and crocodiles.

The snakes and lizards are housed in simple boxes and cages, but the crocodiles, since they require water, present a putting the smaller crocs in old bathtubs while the larger ones live in large galvanized iron cattle-watering troughs.

The water has to be changed and the troughs cleaned every couple of days, but Shwedick says he has no compunctions about climbing in with his crocodiles to do the job.

He almost dotes on his reptiles, and like a proud parent speaks of how much a particular crocodile or snake has grown over the past few months.

But growth is not always all good. Ra, for example, the father of the crocodile Ra Junior, has now grown to a length of 5 1/2 feet and weighs 65 pounds. Shwedick no longer feels it is safe to bring him out on the road when he is making presentations before school children.

"If he got angry or upset, I might not be able to control him," says Shwedick.

Shwedick started collecting reptiles seriously when he was in 10th grade at Prince George's County's Crossland High School, and he says he has been fascinated by them "as long as I can remember."

As early as the age of 12, he says, he kept a pet boa constrictor in the carport next to his house, and he recalls that a python once got loose in his basement and roamed the house for nine months before anyone could find him.

His mother once found herself face to face with a loose crocodile when she walked into the laundry room, and his parents now will not allow most of Shwedick's reptile collection around the house, he says.

His collection is insured for $30,000, Shwedick says. He adds, "I could never replace it for that." It was built up over the years through a series of trades and purchases from other collectors.

"There are dealers all over the United States that buy and sell exotic reptiles," says Shwedick. Purely from an investment standpoint, he adds, there are worse things to be into than reptiles.

A few years ago young dwarf crocodiles were going for around $35 apiece. "You can get more than $300 for one now," says Shwedick.

When he has an appearance scheduled at a school or recreation center, Shwedick typically goes first to his reptile house at 5:30 a.m., loads his reptiles into boxes lined with artifical turf and arrives at his destination by 7:30 for a 9 o'clock show.

Programs can run anywhere from one to three hours. They include short lectures on the characteristics of each reptile in the show, the kind of environment they live in and a discussion of ecology and the need to preserve endangered species.

As he discusses each reptile, Shwedick carefully removes it from its box and holds it on a table for his audience to see.

After he speaks of Iggy the iguana and Myra the turtle, the two are allowed to roam about freely. When the show is over, the children are encouraged to pet the pythons and boa-constrictors. They are not allowed to touch crocodiles or poisonous snakes.

"The kids really enjoy it. He seems to do an excellent job of holding their attention," said John Barbour, a counselor at Lake Waterford Park Day Camp in Anne Arundel County where Shwedick had two presentations last week.

"It was great. I really liked the part about the cobra and when he spread out his hood," said Brian Brown, II, one of the children at the camp.