Slug lovers of the Americas, rejoice! Two more excellent and complementary field guides have been published for the Pacific and Atlantic coasts. Both are by very well known and respected opisthobranch researchers with nearly 100 years of experience between them, and both have over 500 color images to delight the eye.

Up to now Caribbean branchers have had reason to complain about the lack of accurately identified images for reference and species information but no longer. We now have Caribbean Sea Slugs: A field guide to the opisthobranch mollusks from the tropical northwestern Atlantic by Angel Valdes, Jeff Hamann, Dave Behrens, and Anne DuPont, 289 pp. This contains descriptions of 310 species, all with at least one picture and many of them with several showing variation, juveniles, radular structure, and egg ribbons. The geographic coverage extends from Georgia down to northern South America, the Gulf of Mexico, and the islands of the Caribbean Sea. As in all books published by Sea Challengers the print quality and color reproduction is excellent.

A second must-have book is Opistobranquios de Mexico: Guia de babosas marinas del Pacifico, Golfo de California y las islas ocean by Ali Hermosillo, Dave Behrens, and Eduardo Jara, 143 pp. This one covers the fauna found on the Pacific coast of Mexico, the Gulf of California, and the offshore islands, a total of 234 species. The text is in Spanish so English speakers will not be able to fully utilize all the information in the book, but the real value is in the pictures. Like Valdes et al, the authors provide multiple photos for many of the species showing color variation or behavior.

While all of the authors deserve our gratitude, I think special recognition is due to Dave Behrens. Co-author of no less than four excellent books on opisthobranchs published in the last two years, publisher of two of them, commentator for the Sea Slug Forum and the Slug Site, and author of 80 papers in the field, Dave has made an enormous contribution to our understanding of the wonderful world of slugs.

Both books are available from Sea Challengers - in my opinion the very best source of underwater natural history and guide books.