OCEAN ANIMALS : SPONGES, SEA-ANEMONES, ETC. 143 



Among the univalved ocean molluscs there is a great 

 variety in the size and shape and coloring of the shells. 

 Many are beautifully colored and patterned; others are 

 oddly and fantastically shaped. The cowries, or porce- 

 lain shells, familiar in collections of ocean curiosities, 

 have a large body whorl and a very short flat spire, and 

 the brightly colored shell looks as if enamelled. Some 

 of the coast tribes of Africa once used, and perhaps still 



Fig. 106. — The jjiant squid, Ommatostrephes californica. (From specimen 

 with body (exclusive of tentacles) four feet long, thrown by waves on 

 shore of the Bay of Monterey, California.) 



use, to some extent, cowries as money. The limpets 

 are among the most abundant of the seashore molluscs, 

 their low, broadly conical shells being plentifully scattered 

 over the rocks between tide-lines (fig. 105). The oyster- 

 drills are molluscs with odd spiny shells, which do much 

 harm by settling down on the oysters, boring holes 

 through the shells, and eating the soft parts within. 

 The helmet-shells, from which shell cameos are cut, are 

 composed of layers of shell material of different colors. 

 Among the specially beautiful shells are the cone-shells, 

 the olive-shells, the ivory-shells, etc. 



