20 WEST AMERICAN SHELLS 
In the descriptions of species the same order 
will be followed as that adopted for the ‘‘List of 
West American Shells,’’ near the close of this 
volume. There the classification is given in full, 
though the notes about each species are very brief. 
Many of the species will not be described fully, 
for various reasons, most of which have been set 
forth at length in the Preface. But hints and 
suggestions will be freely given to help all who are 
very properly trying to arrange their specimens 
in a natural order. 
The next shell on our list belongs to the Nucu- 
lide, and is named Nucula (Acila) castrénsis, 
Hinds, the Camp Nut-shell. It is well named, 
for the shell resembles a three-cornered, dark 
brown nut, while its sides have sculptured mark- 
ings, reminding one of many steep walled tents. 
Internally it is beautifully pearly, and it has about 
seven little hinge-teeth on each side. The whole 
shell is wedge-shaped, and is about as large as a 
good sized pea, though it sometimes grows a lit- 
tle larger. This species is seldom found on the 
shore, but a large number were dredged off the 
coast of southern California a few years ago. The 
shells are sometimes thickly coated with fine mud. 
It has also been found in Puget Sound, and even 
farther to the northward. 
Nucula suprastriata, Cpr., the Fine-lined Nut- 
shell, has a much smaller shell, and the sculptured 
lines are concentric, instead of forming angles. 
It probably lives within about the same limits as 
the last species. 
