SHELLS WITHOUT CANALS 203 



which properly live their quiet lives, without ever 

 even attempting to murder their neighbors. 



Our first species, Littorina scutulata., Gld., 

 the Checkered Littorine, is shown slightly 

 enlarged in Figure 194. The shell is usually 

 of a greenish or brownish gray color, with^. ,„, , 



^ ^ ^ ' ' _ Fig. 194, X I 



more or less white bands or checks. Within 

 the aperture the fresh shell has a decidedly purple 

 tint. The shells differ greatly in size, young ones 

 being very small, while you sometimes find old speci- 

 mens as large as the picture. 



Littorina planaxis., Nutt., the Gray Lit- 

 torine, is well shown in Figure 195. This 

 species commonly has a somewhat larger 

 ^. ,„^ , shell than the last, but it is easily dis- 



Fig. 195, X 3 . . . 



tinguished by the fact that it has a flattened 

 columella, which seems to be dissolved away by the 

 animal in advance of the growing whorl. The shells 

 of this species are more rounded and less finely col- 

 ored than those of the last, but the two are often 

 found closely associated. Young specimens some- 

 times have shells banded with white, but there need 

 be no hesitation in determining the species, for the 

 flattened columella is a sure mark of identity. 



The third littorine, which is found in northern 

 waters, is named Littorina rudis^ Don., the Rough 

 Littorine. The shell of this bold northerner, in form 

 and size, resembles a large pea. It is easily distin- 

 guished from the last species by its rounded colu- 

 mella, while its general surface, instead of being 

 nearly smooth as in the last two species, is marked 

 with a good number of more or less developed spiral 



