LITTOEINA. 343 



The L. rudis, L. tenebrosa, L. zonaria and L. rudissima are 

 usually inhabitants of the estuaries and muddy oozes, and 

 rarely exposed to the full action of an open sea. 



We earnestly recommend naturalists, in their respective 

 localities, to consign the four species above-named to basins of 

 water, together with all the dwarf varieties inhabiting the 

 crevices of rocks, when they will at once perceive that they 

 are all identical with the type L. rudis; it will afford a 

 practical proof that species founded on the characters of 

 the shells are artificial and delusive, and that the soft parts 

 must also be considered to obtain specific distinction. 



The L. rudis, and all the varieties, are extremely impatient 

 of continued immersion in water ; when deposited in basins, 

 the first object is to escape therefrom, and attach themselves 

 to a dry spot. In estuaries, where they are often aifused by 

 the fresh water, they become, particularly the L. tenebrosa, 

 thin and depauperated in their shells; they are sometimes 

 for weeks deprived of even being sprinkled by sea-water. 

 Though decided Pectinibranchiata, they live in the open air 

 with nearly equal facility as the Pulmonifera ; and in reference 

 to this fact, as regards another family, the Conovulidce, there 

 are still malacologists, who, notwithstanding the valuable 

 observations of the Rev. T. Lowe and M. J. Berkeley, are not 

 quite satisfied that they are pulmoniferous ; we have ourselves 

 attempted to corroborate these views, in our remarks on the 

 PyramidellidtB. 



The L. littorea is the only species of this particular form 

 that requires, to attain full growth, a regular bi-hodiernal 

 immersion in sea- water, and to obtain it, the bulk of that spe- 

 cies live in the lower littoral levels ; if they are deprived of it, 

 they become stunted and dwarf. 



That variety of the L. rudis which is undoubtedly the L. ju- 

 gosa of Montagu, varies from quite smooth to highly striated, 

 and has even, ridged, reflected, spiral volutions, as repre- 

 sented in the figure of Montagu's ' Testacea Britannica ;' it 

 clothes the interstices of rocks on the Devon coasts in myriads. 

 They are rarely or never immersed, as they dwell in the 

 highest levels, in most exposed situations; in like manner 



