1V PREFACE. 
ing parts, if they should appear, must be hailed by the 
friends of science with much less confidence, although 
with equal admiration and gratitude. 
The system of classification desirable to the Geologist, 
is that by which a shell may be readily and accurately 
determined, without considering the’ animal which has 
inhabited it. Such a system is equally convenient to the 
Conchologist, when each genus is followed by a reference 
to the place which the animal occupies in the Natural 
System, which should always be adjoined. To be unable 
to determine the shell, unless we found the animal, would 
be like having no other aid than Crystallography for the 
study of Minerals. u & 
These elements are principally compiled from Cuvier’s 
‘¢ Mémoires pour servir a U Histoire et a Anatomie des 
Mollusques,” and the 2d vol. of the ‘‘ Regne Animal” 
of the same author; M. Lamarck’s Mémoires sur les Fos- 
siles des Environs de Paris ;” M. Brongniart’s “Mémoires 
sur des Terrains qué parotssent avoir été formés sous 0 Hau 
Douce,’ and others on the. same subjects, scattered 
through the 22 quarto volumes of the ‘‘ dnnales du Mu- 
seum ;” M. Blainville’s and M. Defrance’s articles: in the 
‘“< Dictionnaire des Sciences Naturelles ;” M. de Ferussac’s 
“ Histoire Naturelle, générale et. particuliere, des Mot- 
lusques Terrestres et Fluviatiles ;” and many other rare 
and costly wurks, collected in the splendid library of 
Baron Cuvier, to which I have had access at all hours, 
with the liberty. of taking dome, whatever I pleased, for 
the last two years. sh at 
The figures which illustrate the system of M. de Ferussac 
have been copied from those which accompany his work, 
with the, exception of such as were to be found im the 
Museum. Almost all the other figures of the recent, and 
some few of the fossil shells, have been drawn from the 
objects. themselves ; which I have invariably been per- 
mitted to take home, from the Museum for that purpose, 
without being limited either to ume or number. | have 
occasionally been favoured with such specimens as were“ 
not to be found there, from the cabinets of MM. Lamarck 
and Dufresne. be 
