es ek 
(2 1 Av 
by) 
21.59, 7. 
OM 1. 
PREFACE. 
THE aim of the present book was to describe and notice 
a large number of shells in a limited number of pages. It 
was designed, originally, as an abridged translation of the 
excellent edition of Lamarck’s ‘Animaux sans Vertébres’ 
by Deshayes, enlarged by the addition of such species as 
appeared to the writer to be most decidedly distinct from 
any enumerated in those volumes. This selection proved 
embarrassing; since many of the Lamarckian diagnoses, 
being far too brief for the purpose of definition, suited 
fairly enough, from their very succinctness, the characters 
of several subsequently named shells, which otherwise the 
author would have gladly introduced. Up to the genus 
Nucula the plan of the work has been uniform, the species 
of the ‘Animaux’ following each other in numerical suc- 
cession; beyond that point, the author has allowed himself 
a less fettered exercise of his more matured judgment; 
nevertheless, no Lamarckian species has been wilfully 
omitted. 
In the Naiades, the skeleton outline given by Lea in the 
second edition of his ‘Synopsis’ has been accepted as a 
standard authority; because such contradictory opinions, 
a 
