216 WEST AMERICAN SHELLS 
most of the time, and except at high tide they can 
always be found upon the rocks along the shore. 
Each of the little shells has a small spire of a few 
whorls, an entire aperture, a sharp outer lip, and 
a Haat horny operculum. 
Our first species, Littorina scutulata, 
Gld., the Checkered Littorine, is shown, 
heey enlarged, in Figure 232. The 
shell is usually of a greenish gray color, 
Fig. 232,x2 with more or less white bands or checks. 
Within the aperture the shell has a decided purple 
tint. Its length is from one-fourth to one-half an 
inch, and you may sometimes find old specimens 
nearly as large as the picture. 
Littorina planaxis, Nutt., the Gray Lit- 
torine, is shown in Figure 233. This 
species has a somewhat larger shell than 
the last and is easily distinguished by 
the 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 colored than those of 
the last, but the two are often found closely associ- 
ated. Young specimens sometimes have shells 
banded with white, but there need be no hesitation 
in determining the species, for the flattened colu- 
mella is the 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, greatly resembles a large pea. It 
is easily distinguished from the last species by its 
rounded columella, while its general surface, 
Fig. 233, x $ 
