38 WEST AMERICAN SHELLS 
The first in 
importance 1s 
Pécten ae- 
quisulcatus, 
Cpr, the 
Speckled Pece- 
ten, a good 
view of which 
is given in 
Paguiren ales 
This species 
abounds in 
the .sioamnl. 
where it can 
be dredged, 
though good 
specimens are often found at low tide. This crea- 
ture can swim freely by flapping its broad shells, 
though it sometimes moors itself to a piece of sea- 
weed by spinning a byssus with the aid of a singu- 
lar little organ shaped like a finger. You will no- 
tice in the picture a little notch in the back shell, 
just under the left ‘‘ear,’’ through which the little 
creature thrusts out the finger when spinning the 
threads. Ina good specimen you will find that this 
opening is set with little projections, like the teeth 
of a comb. 
Pécten caurinus, Gld., the Weather-vane Shell, 
(Amusium caurinum), is a large species found in 
the north, which has very broad, thin, and flat 
shells, marked by about twenty ribs. The edges 
are thin, the ears small, and the color white within 
