LOCALITIES OF MOLLUSCA. 489 



anfractuosities. Succeeding these, on the level sandflat, 

 you will notice Natica and the glossy Olives, partially 

 covered by their mantles, leisurely forming burrows in the 

 moist soft bed on which they spend their lives ; gaily- 

 coloured Volutes, and apathetic Mitres, with cloaks be- 

 grimed with dirt, crawling about with a slow deliberate 

 motion, wherever there remains a little water ; and when 

 that is gone, and they can no longer enjoy themselves, 

 they sink into the yielding sand, generally, if possible, 

 choosing places where it is mixed with mud. Then come 

 Buccinum, the large-footed Bullia, and Nassa, with its 

 bifid, turned- up tail, considerably more lively than their 

 last mentioned neighbours, of greater latitude in their 

 progressive movements, and which form long sinuous 

 tracks as they traverse on their foot-like bellies the loose 

 saturated sand; Natica and Oliva excavate the surface 

 more deeply still, and move in burrows underneath the 

 soil ; while Venus, Solen, and the light-shelled Mactra per- 

 forate obliquely the loose and moistened sand. At dead 

 low water, among huge stony madrepores and branching 

 corals that serve to form the barrier-reef and break-water 

 to protect those Mollusks that live inside and love calm 

 water, may be found embedded in their substance Litho- 

 domm and Pholas, Magilus and Lcptoconchus, snugly 

 lodged in their calcareous dwellings, secure from every 

 foe; Haliotis will be found clinging to loose stones, or 

 crawling over and under them, exposed ever to the raging, 

 roaring surf ; amid the rocky beds, Tridacna rests secure 

 in her stony house ; Cypraa cowering in the deep nooks; 

 holes, and corners, creeps forth cautiously and with care, 

 frequently hiding under stones so rough and large, that 



