INTRODUCTION. XIX 



nutely explored, numerous Nudibranclnate Gasteropoda 

 will reward the collector. The land will probably sup- 

 ply few additional species. Many years may be required 

 to complete the series. Let a few other individuals 

 meet with equal success, and our Molluscous Fauna will 

 make as respectable an appearance as that of any in 

 Britain. In the meantime, it is hoped, the present work 

 will prove of considerable utility both to students, and 

 to more advanced malacologists. 



It will be found to present a general view of the sub- 

 ject, as well as sufficiently full descriptions of the species 

 hitherto met with. After the general characters of each 

 class, will be found a Synopsis of the Aberdeenshire 

 species, in which are given the generic and specific cha- 

 racters, and etymologies. The genera and species are 

 then more fully described. The measurements are given 

 in twelfths of an inch* References are made, under each 

 species, to various authors who have described it : for 

 example, "Linn, Syst. Nat. i. 1232," that is Linnaeus, 

 Systema Naturae, vol. i. page 1232 ; "Mont. Test. Brit. 

 335, pi. 11, f. 12," Montagu, Testacea Britannica, page 

 335, plate 11, figure 12. Subjoined is a List of the 

 principal works to which reference is thus made. 



As to the Nomenclature I have adopted the usual 

 method of giving to the genera and species the names 

 imposed upon them by the persons who first described 

 them. 



