THE SHELL-FISH OF THE COAST. 29 



along the beach you cannot fail to have noticed 

 peculiar gray, collar-like bodies scattered about, 

 some of them forming almost complete circles, and 

 measuring six inches or more across. Examined, 

 these collars are seen to be made up of minute sand- 

 particles glued together, and if held up to the light 

 exhibit an almost innumerable number of translu- 

 cent spots. These spots correspond to the positions 

 of egg-cases which are distributed throughout the 

 mass in a single layer, and in quincunx order. 

 The whole is, in fact, the egg-ribbon or ' nidus' of 

 the Natica — a construction unlike that; of any other 

 mollusk. Just how it is made still remains a mys- 

 tery, but it appears that as it is extruded in the 

 form of a viscous mass it is immediately moulded 

 over the external face of the shell, which gives to 

 it its peculiar spiral curve. The coating of mucus 

 then draws to it the sand-particles which line it on 

 either side. Two forms of this ribbon occur on 

 our coast — one, a simple collar with a constricted 

 neck, the other, sharply ruffled on its border. The 

 former belongs to Natica heros, the latter to iV". du- 

 plicata. The crowded little pouches, each of about 

 the size of a spangle, which are frequently found 

 on one side of the collar, are the egg-capsules of 

 the dog-whelk (Nassa). 



Of the several other species of marine snails 

 occurring on our coast a few are found only at rare 

 intervals, and not unlikely their shells have been 

 merely washed hither without the animal itself 

 living along the immediate coast-border. Among 

 these are the auger-shell (Terebra dislocata), a com- 



