The new edition is not very different (e.g. 84 pages as opposed to the original's 82, and this has only changed due to the inclusion of a few new references), but it does contain four additional species, some corrections and some updates to the nomenclature (scientific names), quite a few of which have changed. The four new species are:
- Myosotella denticulata. This is very similar to M. myosotis, and they are both species of tidal standlines and edges of saltmarshes. Both key out at the same place, and Cameron doesn't attempt to distinguish the two fully. Further information on separating these species is available in Roy Anderson's 2008 checklist of UK non-marine Mollusca, which can be downloaded from the Conchological Society.
- Balea heydeni. This has been split from the similar B. perversa, and it seems that the 'new' species B. heydeni is actually the commoner of the two in Britain and Ireland, so previous records of B. perversa will have to be classed as an aggregate of the two species unless they can be checked. Balea spp. can be found on trees and rocks (the first edition of the key rather intriguingly says that B. perversa [agg.] is often found in places with few other snails, but this descriptive text has been sacrificed for lack of space in the second edition).
- Papillifera bidens. A Mediterranean species that has been introduced into Britain; the only confirmed records so far are from a National Trust property in Buckinghamshire. Superficially similar to other clausiliid snails but with a distinctive dark band and white spots running round the shell.
- Cernuella aginnica. Another introduced species that has so far been found only in Kent, and is not thought to be widespread. It is very similar to the common C. virgata, and requires dissection to confirm (features described but not illustrated in the key).
And if you don't have the key at all I would recommend it to anyone with an interest in snails - it is a thorough and careful key, but very well laid out and easy for a beginner to get to grips with. I particularly like Robert Cameron's introduction to using the key, which starts:
"Experience has shown that there are two extremes in reactions to keys. One is the expectation that a good key should lead simply to the right answer, even in the hands of a beginner. The other, sometimes expressed by experts, is that keys never work well, and that only face-to-face tuition by an expert works properly. The first view leads to frustration, or even despar. The second can have the effect of making identification an arcance professional preserve."Robert goes on to chart a middle course between these extremes, providing guidance on how to get the best out of using a key, and what limitations have to be borne in mind. He demonstrates this advice well in his own key.