10 INTRODUCTION 



ensconced under projecting surfaces. Most species are more 

 plentiful at the lowest-water mark, and many are found only at 

 this point and below. 



SANDY SHORES 



On sandy shores the greater part of the inhabitants live under 

 the surface. Many give evidence of their presence by the open 

 mouths of their burrows, and some distinctly point out these 

 places by piles of sand or mud in coils at the opening. Some 

 tubicolous worms have their tubes projecting above the surface. 

 The tubes of Diopatra are hung with bits of shells, seaweeds, and 

 other foreign matter. Some mollusks announce themselves by 

 spurting jets of water or sending bubbles of air from the sand. 

 The majority of the underground species, however, give no sign 

 of their presence on the surface, and must be found by digging. 

 Many of them go deep into the sand, and in searching for worms 

 the digger must be quick and expert, or he will lose entirely or 

 cut in two many of the most beautiful ones, which retreat quickly 

 and to the extremity of their holes at the least alarm. One can 

 be a rambler on the sandy beach for a long time without being 

 aware of the many beautiful objects which inhabit the subsurface 

 of the sand. The curious crab Hippa will disappear so quickly 

 into the sand that one is hardly sure he has really seen it. The 

 vast number of worms will surprise any one who searches for 

 them by their variety, their beautiful color, and their interesting 

 shapes. Here again a glass is requisite to appreciate the delicacy 

 and beauty of their locomotive organs, their branchiae, and so on. 

 The most common of the gasteropod mollusks on sandy shores 

 are Nassa obsoleta, Nassa trivittata, and Polynices (Lunatia) heros. 

 The last are detected by the little mounds of sand which they 

 push before them as they plow their way just below the surface. 

 On more southern beaches, Fulgur, Stronibus, and Pyrula are the 

 common varieties. Olivctta, Olivet, and Donax, also inhabitants of 

 sandy beaches, will quickly disappear when uncovered by the 

 waves, being rapid burrowers. Most of the many dead shells on 

 the beach will be found to be pierced with a round hole, which is 



