The International Code of Zoological Nomenclature does not protect names for hybrids. In other words, it does not encourage people to erect names based on specimens that they know are hybrids. A "hybrid" is defined as "the progeny of two individuals belonging to different species"--not subspecies. If a species name is later proven to represent a hybrid, then the name is not protected by the Code. To prevent confusion, the name cannot be used again for any other animal, not even the parent species. Of course, it's not easy to prove that hybrids are hybrids, especially when they breed underwater. Names for hybrids of plants are allowed under the Botanical Code. Plants hybridize more readily than animals, and horticulturists usually know exactly what the parent species are. Roses don't breed underwater. Genetic material is traded asexually so often among bacteria, even bacteria that are not closely related, that the bacteriologists have something quite different in mind when they say "species". They operate under a separate Bacterial Code. Incidentally, hybridization can be another source of beneficial changes in a group of animals, in addition to mutation. In the case of hybridization, the raw material of the genes may be unchanged, but the combination is new. So this is one of the sources of creativity in nature. I think that we need to hear from some people who have some clear examples of hybridization in mollusks, to give us a better idea of the concept. Isn't the common garden snail of California a hybrid of two species, for instance? Which two, and how and when did it happen? Andrew K. Rindsberg Geological Survey of Alabama