48 Rupert Jones, on Bivalved Entomostraca. 



limbs, possess a greater or less power of sAvimniing, Candona 

 being a marked exeeption. On tlie other hand, the anterior 

 locomotive limbs of the CijtheridcB have usually short setae 

 and hook-like spines, instead of bunches of long, delicate 

 filaments ; and consequently these animals crawl about on 

 the weeds, shells, and mud, and few among them can swim 

 at all. 



The Cypridinidae are mostly free-swimming, oceanic forms. 

 Mr. Brady observes that " some of the members of this 

 family have very slight swimming powers, and live chiefly 

 amongst mud; others are very agile swimmers, and are often 

 taken in the towing-net — more especially at night — near the 

 surface of the sea. They seem, indeed, to contribute very 

 materially to the production of the wonderful phosjjhorcs- 

 cence of the tropical seas" (' Intellectual Observer,' 1867, 

 p. 115). 



The removal of dead animal matter is easily accomplished 

 by Entomostraca and other small Crustacea ; and, as the 

 Emmets and their little fellow-labourers pick bare the bones 

 of large land animals, so these minute creatures of the water 

 use up the dead bodies of animals in the ocean, the lakes, 

 and rivers, foraging for the dead zoophyte, and swarming 

 over the lifeless mass of mollusc, annelid, and star-fish, and 

 taking their share of the dead Fish that had lived by eating 

 their fellows,* and of the dead Whale that had strained 

 from the water myriads of their congeners for his daily food. 

 When the sailors, in one of Parry's Voyages, hung their salt 

 beef over the ship's side in the water for a while, it soon dis- 

 appeared under the combined attack of these little devourers ; 

 and if a fish be put in a perforated canister in a suitable 

 stream or pond for a couple of days, its skeleton Avill be pre- 

 pared by the tiny Crustaceans. Just as Mr. Charles Moore 

 has found in the Lias of Somersetshire, the fossil Reptiles 

 overlain by a swarm of Ammonites, buried with the half- 

 eaten carcase in the mud, so the fossil remains of Fishes (as 

 noticed by Phillijjs, Binfield, myself, and others) are often 

 and often found imbedded Avith innumerable carapace-valves 

 of the Entomostracous scavengers in mud-beds of all as^es, 

 especially the Carboniferous, Wealden, and Tertiary clays) ; 

 nor are Entomostraca Avanting among the bones of fish and 

 reptile in the Lias above alluded to. 



Thus also we have seen a crowd of Cyprides and Candonce 

 cleaning out the shell of a Paludina or a Linnmis in an 

 aquarium ; and in the fossil state we know that valves of 



* See Dr. Baird's " Notes on the Food of some Fresh-water FislTes, more 

 particularly the Vandace and Trout." 1S57. 



