SAN JUAN, Puerto Rico: "Aqui Mayaguez, uno. Arecibo, Arecibo, dos. Ponce, Ponce, uno."

The drivers, hanging onto their car doors, shout place names and numbers - an incomprehensible bingo call to the uninitiated, made more so by the occasional trading of an insult and the unpredictable pauses for a bite of spicy alcapurria .

Nevertheless, prospective passengers fill up the small plaza and contribute to the din by yelling for drivers to wait or loudly inquiring about rates and routes. Uniformed children with school books laugh and flirt. Men in starched guayaberas read their newspapers and kerchiefed women with string shopping bags broadcast whatever news Radio Bemba (slang for gossip) has that is hot. Everybody scuttles back and forth like newts, suddenly, darting in and out of the parked cars and along the narrow sidewalk.

And at the center of it all is the Hispanic cross between private and mass transportation - that marvelous device known as publico .

Many Colombians I know prefer them. Mexicans make special arrangements with them. Cubans remember them fondly. Dominicans and Puerto Ricans depend on them. The publico, this common means of transportation in the Spanish-speaking Caribbean, is the ancestor of our gypsy cab.

For the tourist to the Caribbean, the publico - known in different locales as a carrera, pesero, maquina de alquiler - is not only a satisfying and cheap way of getting from one place to another, it also offers the unique bonus of quickly putting the visitor in touch with the true native culture of the host country. A publico can let you directly experience those subtle aspects of culture not governed by heredity nor easily learned in school nor on gaudy display in a nightclub - greetings, gestures, postures, flirtations, bargaining and imprecations.

I don't mean to suggest that what takes place in these vehicles is exotic. I'm talking about everyday behavior in societies which are still familial, where traveling in a publico is a daily extended-family reunion. A ride in a publico is a way to experience the love, heat and intimacy of a national family that is denied tourists in most encounters with "natives."

Ultimately I suppose these vehicles are careless reminders of the low priority that Caribbean governments place on public transportation, but that's another story.

Publicos look like taxis, but have no meters, carry multiple fares, make inter-city trips and cross-island journeys, as well as intercity hops. They can be hailed from city streets as well as from highways, travel from the carefully groomed thoroughfares of an international airport as well as around the bathtub rings of alien culture found in the urbanizaciones outside large cities.

Publicos carry no advertisements nor do they have an identifying light on the roof to indicate whether a vehicles is on or off duty. Publicos congregate at stands as well as cruise and have a yellow tabiila (license plate) which says "Publico" - admittedly hard to see when it is traveling down the carretera at 100 kph.

Since there are no meters, one must bargain. Speaking Spanish, as my wife and I do, is a distinct advantage. I never ask the driver at the Rio Piedros publico stand what the price is to Farjardo, I suggest an amount. He is obligated to respond by telling me how much gasoline costs, that he had two kids going to private parochial schools and that food prices - especially rice - are altos . I then come back with a compromise. I say that my youngest children will sit on our laps and in this way he won't lose two fares. He in turn lets me know that he's going far out of his way and that he'll probably make the return trip empty.

Finally we agree. My wife and I will help fill the publico with other Americanos at the airport, my youngest kids will sit on our laps and our suitcases will go under our legs. We - two adults, four kids, 25 pounds of paper diapers, a crib on the roof and two other tourists - are off.

The driver, Julio, is talkative and strongly opinionated. My wife and I are quickly brought up to date on Puerto Rican politics. Neoriquenos (Puerto Ricans from New York), according to Julio, are responsible for everything from an increase in food prices to bad weather. Dominicans are poor tippers and are too arrogant about their baseball players. Cubans have too many privileges.

All during the trip, Julio continues to ventilar (to speak his mind), even as he picks up and discharges passengers, waves to friends and challenges other drivers to heart-stopping races. In addition to having mastered the Italian tacapunto style of never losing an rpm, Julio drives as if he were fleeing a tidal wave, slowing only when the alternative is a fiery death ahead. His rhythm is accelerator, clutch, accelerator, brake, beep, accelerator, brake.

As with many cultural adaptations, whether it be a parliamentary form of government or an automobile horn, foreign institutions simply do not grow exactly the same way when transplanted to another soil. The horn on Julio's Chevy for instance is not merely a way of warning viandantes (pedestrians) and cars, it is his signature, a way of identifying himself. As we approach neighborhoods and intersections, Julio toots da-duh-duh-da-da. Another driver sounds duh-duh-duh and a sagging Buick fires back a simple but swinging duh-duh-dadada.

Enroute to Fajardo, we stop at an intersection far from San Juan and still kilometers from our destination. Julio turns off the engine and chats with a highway patrolman who has parked his patrullero on the shoulder of the highway. When the socializing is over, we leave the road to discharge our other traveling companions and fill the tank with gasoline.

At the service station, we continue our education in Puerto Rico's culture. Julio purchases an orange from an old man's painted push cart. Near the cart's handle is a mysterious piece of metal. We find out that in Puerto Rico an orange is a china and that Puerto Ricans prefer them as snacks. We also learn how Puerto Ricans eat chinas. (One day I'll write an extended orange peeling psychological profile of national character, but that, too, is another story.) The metal Rube Goldberg apparatus perfectly skins the china leaving only the thinnest film of white pectin. A hole is then cut in the top of the orange and the hand holding the fruit squeezes the juice into the mouth.

Not only did we, too, become appreciative fans of chinas, but at this stop we also ate a habit-forming Puerto Rican candy called dulce-de coco (coconut goody) and the kids hungrily ate a whole bunch of 2 1/2-inch bananas called guineos - surely as sweet as when Colon (Columbus) learned to eat them from the original natives of this island.

Listening and watching at publico stops and talking to other passengers, we understood that despite 80 years of economic and political association with the United States, once you are away from San Juan, Puerto Rico remains a Hispanic country. We also learned more immediate lessons, like closing our eyes when going around a turn and how to sit next to a rooster without concern.

For Julio's passengers their driver is not merely a steerer of machinery, he is a social institution as well as a message carrier and automotive warrior. He is a man of considerable status and respect. Many of the people he picked up are regular customers. Each was greeted in familiar terms with good-natured ribbing. Julio is not a wealthy man. A quick calculation by my wife revealed that with full loads and about 10 hours of driving seven days a week he might clear $100.

Julio got us to our destination. He helped us unload all the suitcases and the crib and accepted our invitation for a cafecito . In spite of our early haggling, he sat with us for a good half-hour - his curiosity about us seemed as important to him as additional fares.

We came away from our encounter with Julio, and subsequently with many Julios, convinced there is no better and quicker way to know and appreciate the warmth and Hispanidad of Puerto Rico than a ride in a publico.