PIERCED SHELLS AND CHITONS 257 
shell is thin, the edge sharp, the spire quite promi- 
nent, the surface uneven, and the four open holes 
large and surrounded by high walls. A deep chan- 
nel runs under the line of holes. The interior is 
very iridescent, a light color prevailing, and the 
muscle-sear is not distinct. 
After the shells which have several holes, which 
we have just considered, there come a number 
having only one opening, which answers the same 
purpose. First, we will consider Puncturélla 
major, Dall, the Greater 
Puncturella, Figure 
289. It is not a com- 
mon shell, but it shows 
the features of the 
genus in a fine manner. 
Its color is white, its 
internal margin crenu- 
late, and the posterior 
slope slightly arched. 
This fine, large shell 
was dredged in Bering 
Sea. Fig. 289 (*) 
Puncturella galeatea, Gould, the Helmet Pune- 
turella, is an inhabitant of Puget Sound and adja- 
cent waters. The shell is conical and elevated, 
being about as high as it is broad. The fissure at 
the summit is narrow, and internally there is a 
little pit on each side of the hole-channel. Color 
whitish; length 10mm. 
Puncturélla cuculata, Gld., the Cap Puncturella, 
is found in Puget Sound, also at Monterey. The 
