Volume 156: Biology of the Opisthobranch Molluscs. Volume 2. T.E.Thompson and G.H.Brown. 1984.

This is the second of two volumes on the Opisthobranchia, and gives a systematic account of the British Nudibranchia.  The nudibranchs constitute the largest opisthobranch order, with 108 species in 4 suborders.  In this compilation, as in volume I (published by The Ray Society in 1976), every effort has been made to verify previous descriptions, to compare British representatives with their European and north American equivalents, and to present new illustrations in both colour and black and white.  Dichotomous keys to species are provided, and an especially useful feature of the volume is the pictorial synopsis, where line-drawings illustrate the British naked (i.e. shell-less) opisthobranch molluscs.  Original colour plates from life depict all but a very few of the British species of nudibranchs. 

The Opisthobranchia  are popular with marine biologists and with general zoologists because of their common occurrence and their often vivid colours and elegant behaviour.  They are a subclass of the gastropod molluscs, and all are hermaphrodite, marine and macroscopic.  Worldwide there are about 3,000 species, and around 150 of these have been recorded from the shallow waters around the British Isles.  Of the British species, 30% are infaunal, the rest epifaunal.  It is chiefly the epifaunal type, exemplified by the aplysiids or the nudibranchs, which has attracted the attention of naturalists for the last century and now, in the nineteen-seventies, has captured the interest of the growing body of aqualung enthusiasts.  

This volume is complementary to the pioneering monographs on the British nudibranchs published by the Ray Society in 1845-55 (by Joshua Alder and Albany Hancock) and in 1910 (by Sir Charles Eliot).