XXX11 INTRODUCTION. 



the smaller terrestrial species,which have been earned 

 there by the rain waters. This should be particularly 

 observed, because conchologists have sometimes, 

 from this circumstance, confounded land shells with 

 those that belong exclusively to the water. To 

 avoid such errors, it will be proper for those who 

 are not well acquainted with the subject, to collect 

 none but Avhat are alive, either in the water, or on 

 the aquatic plants. On the Nymphcea, or water lily, 

 the Hippuris, or mare's tail, the Potamogeton, or 

 broad-leaved pond weed, the Lemna, or duck weed, 

 and the Juncus, or rush, shells may be found in all 

 stages of their growth, with their natural colours, 

 and in the best state of preservation. Most of the 

 species are apparent upon the surface of the plants ; 

 but some of the smaller kinds hide themselves 

 within the folds of the leaves, and it is not uncom- 

 mon to find a pretty little reversed shell, the Bulla 

 fontinalis, wrapped in the leaf of the common water 

 flag. 



The third division of shells, or those that inhabit 

 the sea, are more abundant in their species, and 

 generally more brilliant in their colours, than either 

 the land, or fresh- water kinds. The beauty of their 

 tints, and the elegance and variety of their shape, 

 have made them greatly esteemed by collectors ; 

 and, as mankind will ever be stimulated to exertion 

 by the hopes of gain, sailors, and persons wholly 

 unacquainted with conchology, have thought it 



