PKEFACE. IX 



the curious ; and the details are more easily followed 

 out, from the very fact of the facility of observing 

 many specimens at the same time, in different states 

 of development : so that, to the philosophical concho- 

 logist and reflecting student, the most common speci- 

 mens may do more to illustrate the perfection and 

 all-seeing wisdom of the Creator, than the most costly 

 collection. In the description of the species, parti- 

 cular attention has been paid to dividing them into 

 small groups, to facilitate their determination ; and an 

 attempt has been made to point out the different 

 varieties that occur, not by describing each individual 

 variety that may be found, but by indicating the 

 points that have been observed to be most liable to 

 variation, and also the monstrosities which, from the 

 mode of formation of the shell, and some peculiarities 

 in the habit of the different species, are likely to 

 take place in each of them. To illustrate the animals 

 of the different families and genera, a series of vig- 

 nettes has been given ; and further to assist in deter- 

 mining the species, some wood-cut figures of different 

 parts of the animal, as the jaws, teeth, operculum, 

 &c. &c., and of the shells, have been interspersed in 

 the text. 



All the new species introduced into the work, and 

 the more remarkable varieties, have been figured, 

 and added to the plates (except Vertigo angustior, 

 Avhich could not be procured) ; and the whole of the 

 fio-ures which were sjiven in the former edition have 



