From the preface:
"This is the third edition of the FBA's key to flatworms, following on from the second produced in 1978 and the original written over 30 years ago (1967). During the intervening years there has been a steady demand for the key, and a reprint or new edition was needed. Fortunately, Professor Reynoldson and Dr Young agreed to provide us with a completely new edition, including a recent addition to the British fauna. Thus Professor Reynoldson’s earlier key has been substantially rewritten to include twelve species in the main key to live specimens, as well as an additional short key to preserved specimens. This attention to preserved material will be most welcome to those involved in large routine monitoring programmes where preservation, prior to sorting and identification, is a necessity. The authors have included a considerable amount of recent information on the general biology of triclads as well as species-specific biology and distribution, so this edition is more than twice the size of the second one. The number of references (over 150) is also much greater than in previous editions. The new publication therefore is more than just a key; it is a complete key and comprehensive account of the biology and distribution of freshwater triclads in Britain and Ireland. [...] "