The previous volume in this series dealt with twelve species of large flatworms, macroturbellarians. Here, the author has extended coverage of the Turbellaria by producing a series of keys which, for the first time, enable the user to identify 56 species of free-living microturbellarians that currently have been recorded from Britain and Ireland. Like the larger triclads, they occur in a wide range of freshwater and brackish habitats but are less widely known, perhaps because of their small size. With a body length often less than 3 mm and a lanceolate shape, popular methods of collecting benthic macroinvertebrates may result in the escape of these small microinvertebrates through the relatively coarse meshes of most pondnets. Unfortunately, preservation of pond-net samples results in microturbellarians being reduced to insignificant, dull-coloured masses. Hence this key includes informative and essential sections on collection. preservation (for histological examination) and methods of identifying live animals.
The occurrence of some species in temporary, brackish and polluted waters suggests that the group may be useful as part of a monitoring programme for water quality. The clearly illustrated keys provide biologists with one of the necessary tools to investigate this possibility as well as providing an incentive to look for previously undescribed species.
The author has also produced a comprehensive summary of the literature on the general biology and ecology of the group, much of which is available only in German. All who are interested in microturbellarians will have cause to be grateful for the inclusion of this information.