Vlll PREFACE. 



been observed to be most liable to variation, and 

 also the monstrosities which, from the mode of forma- 

 tion 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 vignettes has been 

 given ; and further to assist in determining the spe- 

 cies, some wood-cut figures 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, 

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

 figures which were given in the former edition have 

 been compared with the specimens, and corrected 

 where required. There have also been added to these 

 plates other figures of the same species, and enlarged 

 details of those parts of the smaller kinds which are 

 calculated to facilitate the determination of the spe- 

 cies. Indeed, although this work has been called in the 

 titlepage a new edition of Dr.Turton's Manual, it may 

 be almost considered a new publication, as the only 

 portions of the former edition that have been retained 

 are the descriptions of the species, and a few of the 

 general observations ; in so much that, on revising it in 

 its printed form, it is a matter of regret to me, that it 

 was not rather undertaken as an entirely new work, 

 which would not have cost me nearly so much trouble 

 as editing the present one. 



I have only further to return my thanks for the 



