16 man's influence on higher crustaceans, 



on the beach in such numbers that it appears to be strewn 

 with long stripes of chafif. Only in the Channel Islands, as 

 at Jersey, are the members of this group {Mysidce) captured 

 by fine nets in masses by men in boats, to be utilized as 

 ground-bait in rod-fishing for mullets \ 



Besides these swimming (pelagic) forms the higher crusta- 

 ceans inhabiting the bottom, such as the shrimps, prawns, edible 

 and shore-crabs, the hermit-crabs and lobsters, continually send 

 up a series of larvae to join the free-swimming multitudes, and 

 at a later and larger stage they again pass to the bottom, thus 

 giving the fishes a double opportunity, the smaller seizing 

 them on their upward journey and in their pelagic stage, 

 the older and larger as they descends The circulation of 

 such larval and post-larval crustaceans in the ocean is thus 

 an important factor in the food of other marine animals. 



With regard to the edible crustaceans it cannot be said 

 that man has yet made a notable reduction on the shrimps and 

 prawns so largely captured on many of our shores for food. 

 Where they formerly occurred in great numbers they still 

 prevail; where they are fewer, and where no diminution has 

 been caused by man, they remain as before, without any 

 apparent increase. 



It is otherwise with the large slow-growing lobsters and 

 edible crabs, the numbers of the former, especially in our 

 own country and on the shores of Canada, having shown 

 signs of diminution during recent years, from the exertions 

 made to capture them for food. The lobster in its adult con- 

 dition is chiefly an inshore form, and thus is easily reached by 

 the instruments for capture ; while its slowly developing eggs, 

 attached to the abdomen of the female nearly a year, encounter 

 many risks, irrespective of the capture of the adult. It is a 

 species, in short, which readily yields to adverse forces, though 

 at the same time there is no sign of extinction. Its chief safe- 

 guard is the pelagic stage of its larva, but as the adults are for 

 the most part inshore forms, and the free-swimming stage 



^ J. Hornell, Jour. Marine Zool. and Micros., ii. 1897, p. 90. 

 2 Vide Trawling Report, 1884, p. 370, 



