In
this second volume, most of the families not included in volume 1, are covered
(volume 1 treated 25 families, volume 2 72 families). Whilst volume 1 was essentially
dedicated to groups favoured by collectors, with a bias towards species over
5 mm in length, volume 2 encompasses an equally important array of families
and genera, many of which, such as the marine mussels (Mytilidae and allies),
ark shells (Arcidae and allies), pearl oysters (Pteriidae) and rock oysters
(Ostreidae) are of major ecological and/or commercial significance. 775 species
are depicted on (mostly) colour plates.
Also included is an addendum to volume 1, covering recent name changes, colour
photographs of newly described species, and a selection of species which for
space constraints were omitted from volume 1.