PREFACE. 



The following; Treatise is intended as a Manual to 

 Conchologists residing at a distance from the coast, and 

 whose personal opportunities of collecting are conse- 

 quently limited to our Land and Fresh Water Shells, 

 now ascertained to be pretty numerous in species since 

 the time of Colonel Montagu, and my distinguished 

 friend Dr. Leach, whose decease, in the prime of life, 

 was a heavy loss to science. Among those that have 

 materially extended the number of species may be par- 

 ticularised, J. G. Jeffreys, Esq., Swansea; Professor 

 Forbes, King's College, London ; Joshua Alder, Esq., 

 Newcastle-upon-Tyne; and the Rev. Leonard Jenyns. 

 For an extensive acquaintance with the Irish species, 

 I am indebted to William Thompson, Esq., Belfast ; 

 Robert Ball, Esq., Miss Mary Ball, and T. W. Warren, 

 Esq., of Dublin. To the Rev. J. B. Clarke, of Tuam, 

 I am under a deep obligation for the use of his beautiful 

 and correct delineations of the Limacidse figured in 

 plates 25 and 26. 



I have endeavoured to render the Work as complete 

 as possible, by illustrations of all the authenticated spe- 

 cies, as well as of many varieties. These have been 

 represented in different positions, so as to convey the 

 most perfect idea of the form of the species ; amounting 

 to upwards of three hundred and thirty figures. Having 

 collected specimens of the beautiful genus Anodon from 

 distant and wide-spread localities, I have been enabled 



