Fools, Swamps, and Marshes 35 



themselves into their shells when dried. Their slime prevents desic- 

 cation and they conserve water by excreting uric acid. Bassindale 

 (1942) studied the toleration of amphipods on the coast of Great 

 Britain for various salinities. Gammarus pulex was intolerant of 

 salt and tidal rhythms; G. duebeni (+20-25), G. zaddaci (+28), 

 and G. locust a ( + 28) had some toleration for various salinities, 

 and Marino gammarus marinus was markedly stenohaline and found 

 only in the sea. 



Most people think of mosquito larvae as characteristic of stag- 

 nant pools. Arnett (1950) has given an excellent account of the 

 habitat preferences of those in Panama. He makes the following 

 groups of situations with the number of species indicated that have 

 been found in each: 



Surface water 

 Flowing 



Shady 5 



Sunny 9 

 Stagnant (Permanent) 



Shady 13 



Sunny 25 

 Stagnant (Temporary) 7 

 Crab holes 2 

 Aerial habitats 



Close to the ground (Buttress roots, bamboo sections, 



coconut shells, palm spathes, etc.) 10 

 Leaf and flower bracts of terrestrial plants 6 

 Tree holes 9 

 Epiphytic bromeliads 5 

 Artificial containers 10 



Arnett also states that classifications might be made on the basis 

 of toleration to salinity or whether water is foul, clear, turbid, etc. 



