100 



THE CRUSTACEA 



ticidae, and Cyclopidae, are very abundant in fresh water. Most 

 of the Gymnoplea are pelagic, forming a very important part 

 of the plankton of the sea and of lakes. The non-parasitic 

 Podoplea, on the other hand, with the exception of a few pelagic 

 groups like the Co -aeidae, belong to the bottom-fauna. 



A large 



Newly hatched larva of Aryulu* foliaceus. a', an ten mile ; f", antenna ; md, mandible nnJt, 

 in ulibnlar palp; w/', maxilla (lirst maxllliped) ; mf", (second i .maxilliped ; j*i, p*, liibi and 

 lo th pairs otavriHuning-b . .. (After Clau.s, ivoiu Korsc-holt and' Heuier'i KmbryUcxju.) 



proportion of the parasitic forms of various families attack fish, and 

 some of these, such as Lernaeocera and Achtheres, occur in fresh water. 

 Pennella is sometinu-.s found on whales. Other parasitic and semi- 

 parasitic forms JUT found on various groups of marine inverte- 

 brates. The Bran, 'ura are temporary parasites on fish and occur 

 both in the sea ami u fresh water. 



Most of the f n - ''vin^ Kuoopepoda are minute, but some of ihe 



