40 WEST COAST SHELLS 



quantities, though good specimens are often found 

 at low tide. This creature can swim freely by 

 flapping its broad shells, though it sometimes moors 

 itself to a piece of seaweed by spinning a byssus 

 with the aid of a singular little organ shaped like 

 a finger. You will notice in the picture a little 

 notch in the back shell, just under the left ''ear," 

 through which the little creature thrusts out this 

 finger when spinning the threads. In a good speci- 

 men you will find that this opening is set with little 

 projections, like the teeth of a comb. 



Fecten caurinus^ Gld., the Weather-vane Shell, is 

 a species found in the north, which has very broad, 

 thin and flat shells, each marked by about twenty 

 ribs. The edges are thin, the ears small, and the 

 color is white within and light brown without. Its 

 diameter is sometimes as much as five or six inches. 



Fecten diegensis^ Dall, the San Diego Pecten, 

 sometimes grows nearly as large as the last species, 

 though it is totally distinct. Its two valves are 

 dissimilar, the one being nearly flat, while the other 

 is moderately arched. Both have very large and 

 distinct ribs, twenty or more in number, with deep 

 channels between them. The shells vary in color 

 from dark red on the flat side to yellow on the 

 curved. It is found living at least as far north as 

 Monterey, though as its name indicates, its home is 

 in the south. 



Figure 20 represents an exquisitely beautiful spe- 

 cies which is essentially a northern, deep-water 

 inhabitant, though it is occasionally found quite far 

 down the coast. The shell is thin, the ears are very 



