iv 
ment of Testacea,” whose Comparative and Synoptic Tables of the Systems 
of Linnzeus and Lamarck, together with his judicious observations, will 
afford the greatest assistance. 
Tuose Genera which are only to be found in the Fossil state are described 
in their natural arrangement, but are brought together in the last two plates, 
for the convenience of easy reference. 
Some apology may be deemed necessary for the delay which has occurred 
in preducing this work so long after its announcement; to those who are 
acquainted with the vexatious casualties of Lithographic printing, it will 
be unnecessary ; but to those who are not, it may be proper to state, that 
many of the drawings, from the breaking of the stones, and other accidents, 
have been redrawn three or four times over; these and the delays occasion- 
ally experienced in procuring specimens of some of the rarer Genera must 
be my excuse. 
I cannot omit this opportunity of returning my best thanks to Mrs. 
Mawe, Mr. G. B. Sowerby, and Mr. J. D. C. Sowerby, for their kind as- 
sistance in furnishing me with many specimens from their rich and exten- 
sive Cabinets; also to J. G. Children, Esq. for his polite attention in allow- 
ing me access to the collection of the British Museum. 
To avoid repetitions in the following pages, where the authority is not 
mentioned, the specimens have been taken from my own Cabinet. 
E. A. C. 
-_ 
