HINTS FOR COLLECTING. 231 



Ancylus fluviatilis adheres to rocks and stones in running 

 water. Tlie larval cases of Phryganece, or "caddis- 

 worms/^ are now and then studded with Valvata, Pla- 

 norbes, and Pisidia. 



Marine shells have an equally varied habitat^ and are 

 far more numerous in species. Many live between tide- 

 marks, under loose stones_, on seaweeds, or burrowing 

 in sand. The laminarian zone, or the lower part of 

 the littoral zone — whichever it may be called — affords 

 nourishment and shelter to otlier kinds, particularly 

 RissocB. These may be got by washing a quantity of 

 the smaller and finer seaweeds in a tub of fresh water ; 

 they are thus killed and fall to the bottom. The 

 "spolia marina" and drifted shell-sand which are 

 thrown up on sandy shores, especially during and after 

 storms, and which fringe the line of high water, the 

 refuse from trawling-vessels, and the stomachs of fishes 

 and starfishes should be examined; and the deep-sea 

 fishermen may be induced to bring home rare whelks 

 caught on their lines, which sometimes fetch much 

 more than a ling or codfish. 



Oceanic or floating mollusks are procured with a 

 towing-net. This may be a bag of flag- bunting, sewn 

 round a wooden or wii'e hoop about a foot in diameter, 

 and secured to a strong line by three pieces of whip- 

 cord, each from 15 to 18 inches long, which are fastened 

 to the hoop at equal distances, with the ends tied to- 

 gether. At the bottom of the bag there should be a 

 small oval bottle to keep it steady and receive some of 

 the animals. The net is towed astern, clear of the 

 ship's wake, or held in the hand. The length of the 

 line will depend on the speed of the vessel at the time, 

 and on the amount of strain caused by the partly sub- 

 merged net. 



