IN A LITTLE shop around the corner from your European hotel you find just the thing to bring home to good old Uncle Charles -- a cigarette lighter in a shiny gold case trimmed front and back with panels of beautifully marked brown shell. The price looks right and you're tempted sorely when the salesman insists that lots of American tourists buy then and you can legally take them home.

Don't believe him and don't buy it.

And don't buy that handsome pair of shoes, men's or women's trimmed neatly over the vamp and heel with decorative patches of crocodile or python or lizard skin. Even when the salesman swears he sells them all the time to American travelers.

The salesman may very well sell them innocently, buy you will not get either the tortoise shell-trimmed cigarette lighter or the crocodile-trimmed shoes into America. And you may have a few embarrassing moments when you are halted by an alert Customs inspector whose action is quickly reinforced by an inspector from the U.S. Fish and Wildlife Service.

Because you have innocently or deliberately subjected yourself to a possible fine of up to $20,000 and/or a jail sentence of up to one year in a federal pen, these officials will politely, but firmly, confiscate your illegal purchases which are made with items from a long list of creatures on the federal endangered species list.

Wildlife on that list, whether live or stuffed, and articles incorporating their parts may not be imported into the United States commercially or as personal possessions of a returning tourist. When forfeited, that cigarette lighter and those shoes will join crocodile and lizard wristwatch straps and belts, irovy bracelets, tortoise shell combs and bracelets, polar bear rugs and sealskin jackets, beautifully handbags made of the skins of all kinds of crawly things, carved ivory from elephant tusks and walrus teeth, scrimshaw, valuable spotted-cat fur coats and the thousands of other unusual foreign purchases now stored in Fish and Wildlife Service warehouses around the country.

They all were forfeited by returning tourists whose homecoming (if not the previously happy recollections of their travels) were spoiled by ignorance of the laws, treaties and international agreements protecting more than 700 varieties of wildlife -- animals, birds, reptiles, marine mammals -- and plants which are recognized as endangered or threatened. In addition, there are thousands of other varieties which, while not endangered, are protected by foreign nations. The agreements include laws passed by the U.S. Congress and by legislatures of the 50 states, and laws enacted by more than 50 foreign countries. The primary purpose is to protect the many species of wildlife whose existence is being threatened by man's increasing encroachment of their native habitats and his commercial use of their various parts.

The Fish and Wildlife Service of the Interior Department works diligently to acquaint travelers with these restrictions, publishing a free 16-page booklet that explains the pertinent regulations. Today's international traveler has little excuse for being ignorant of efforts to preserve disappearing species, but he or she need not worry too much about the large fines and prison terms that threaten violators. In most cases, the government is satisfied if the illegal item is seized and forfeited, and close the case forthwith. Commercial transport and sale, and efforts at smuggling are the principal targets.

But confiscation of purchases at ports of entry can run into big money. Last year, for example, Fish and Wildlife Service seizures at all ports of entry totaled a declared value of $3 million. Jerome S. Smith, special agent in charge of the Fish and Wildlife Service's District 12, which embraces New York State and New Jersey, estimates 90 percent of that was taken from improperly documented commercial shipments and from would-be smugglers, but the remaining 10 percent from pleasure travelers amounted to $300,000, which represents a complete and total loss to the shoppers.

Recently, at one of the service's warehouses, I saw a rack of 13 spotted-cat fur coats -- of leopard, ocelot, tiger, jaguar and margay skins -- all confiscated from innocent tourists who bought them abroad in good faith. Imagine their surprise and financial shock when the inspectors politely removed the coats from their shoulders -- the retail price of those coats, I was told, can run up to $15,000 each!

The high-priced luxury shopping represented by this rack of coats apparently is not uncommon among upper-bracket American tourists. Smith said his office maintains a secure cold storage fur vault somewhere in New York City that is chock-a-block with equally valuable spotted-cat fur coats. (For obvious reasons, the vault's location is not for publication.)

Fish and Wildlife Service agents have seized so much illegal material that their warehouses are bulging. Efforts are not underway to clarify the regulations so that in a few weeks the General Services Administration may be able to hold auction and sealed-bid sales to dispose of that part of the confiscated stock that may be sold legally. Spotted-cat furs are categorized as an endangered species, and since they cannot legally be sold by anyone in this country, they may not be sold by the government at its warehouse sales.

Asiatic elephants are endangered so ivory from their tusks may not be sold, whereas African elephants, while controlled by their governments to protect them against overkill, are not considered endangered. African ivory, when accompanied by the proper official papers from their governments of origin, can be brought into this country legally. Those now in custody, seized by the Service for lack of documentation, may be put up for sale at the GSA auctions.

The fur coats and other endangered species items cause problems for the overstocked warehouses. Since they cannot be sold and are too rare and ecologically important to be destroyed, the Service is loaning them and similar items to museums and universities around the country. The thinking, Smith explained, is that unless man moves promptly to save these endangered species, future generations may have no other means of learning what those animals looked like other then by staring at these coats in museum displays.

The difference between endangered and protected species is demonstrated along the Mexican border. Many small animals are protected by Mexican laws but may be legally exported thence and imported into the United States with a proper official export permit. Unfortunately, many travelers believe the eager sales clerks who tell them they do not need permits, or they do not want to take the time or expend the effort to get the paper work done. As a result, they lose their purchases without recourse at the customs barrier, and Fish and Wildlife offices in the Southwest have a surfeit of such curious.

The service would prefer to concentrate on intercepting smugglers and improperly documented commercial shipments, rather than dissipate its efforts on pleasure travelers. Tourists, at any rate, should become wary buyers and become informed as to what they may purchase before they leave home. The service's booklet should be read carefully by anyone contemplating any kind of gift and important souvenir shopping overseas. The booklet may be obtained free by writing the Publication Unit, U.S. Fish and Wildlife Service, Washington, D.C. 20240.

If, after reading the booklet, travelers have questions about particular purchases they intend to make abroad, Alan M. Leavitt, chief of the service's office of current information, suggests they write to the Fish and Wildlife District Law Enforcement Office, Washington, D.C. 20240, or telephone (202) 343-9242. His best advice, Leavitt says, is that if after all such study, when you get overseas you are still in doubt, "Don't buy it, for the chances are good you will not be able to bring it back into the country with you."

The Service hears this argument most frequently from travelers whose purchases they are confiscating: "But the animal (bird, fish) was already dead when I bought this article, so what harm am I doing in bringing it home?" The harm, Leavitt explained, is that this purchase increases the consumer demand for such products and probably will lead to the killing of additional endangered animals to restock that little shop around the corner from your hotel.

While the largest flow of endangered species items is into the United States, an unusual and more innocent reverse trend has recently developed.

In Asia, and particularly in China, powdered rhinocerous horn is believed to be useful as an aphrodisiac and for medicinal purposes, but rhinos are almost everywhere endangered and protect, and thus their horns are becoming scarce. Because of this shortgage, the aphrodisiac myth has been conveniently and commercially spread to deer and elk antlers. There is an abundance of naturally discarded horns abandoned in American forests by shedding deer, and they are being searched out and shipped to Asia. At the National Elk Refuge in Wyoming, Boy Scout troops have been organizing search parties to collect the antlers.

This activity poses no threat to the U.S. deer or antelope population, and neither animal is on the endangered list. No decision has yet been reached as to which group raises more funds for their organizations -- Girl Scouts selling cookies to Americans with a sweet tooth, or Boy Scouts selling antlers to Asiaticsin dire need.