210 WEST COAST SHELLS 



brown epidermis, somewhat shaggy, while within it 

 is beautifully white. The length of this fine shell 

 is an inch and a half. 



There is a series of white shells, dead 

 specimens of which are abundant, which 

 present a rather puzzling aspect, and 

 which vary greatly in external appear- 

 ance. They are not spiral to any extent, 



FiK.203 ri I n 



but appear like hollow cones, more or 

 less flattened, with the apex to one side of the cen- 

 ter. Some of them are singularly like a horse's hoof 

 in shape, while others resemble Figure 203, which 

 represents the species named Amalthea antiquata^ 

 Linn., the Ancient Hoof-shell, {Hipponyx antiqua- 

 tus). Some specimens are less flattened than the 

 picture, but all are more or less rough and scaly 

 externally, while within you can see the muscle-scar 

 in the shape of a horseshoe. The color is white, and 

 the diameter is about half an inch. Occasionally 

 living specimens may be found attached to a rock. 

 They do not roost upon the rock directly, however, 

 but upon a little shelly plate which the foot of the 

 animal secretes and fastens firmly to the rock below. 

 Amalthea cranioides^ Cpr., the Flat Hoof-shell, 

 resembles the last species, but has a still flatter shell, 

 with the apex somewhat near the center, instead of 

 at one side. Dead shells of this species, and even 

 of the last, are liable to be confounded by the young 

 collector with the upper valves of the Chama. Both 

 shells are frequently thrown up by the waves which 

 sweep over rocky ledges, and they look so much alike 

 that one miglit almost be excused tor making the 



