A LIST OF THE EHODE ISLAND COPEPODA, PHYLLOPODA, 

 AND OSTRACODA WITH NEW SPECIES OF COPEPODA. 



THREE PLATES. 



LEONARD W. WILLIAMS. 



The Entomostraca, the class to which these orders belong, is a 

 group of Crustacea which in vast numbers inhabits nearly all bodies 

 of water, fresh or salt. The economic value of these minute forms 

 at first glance seems slight, but their importance as a food supply, 

 the effect of the numbers which live as parasites on fish, and the work 

 they perform in destroying other still more minute forms, injurious 

 to fish, make them a group by no means negligible by the practical 

 fish culturist. Many small fish undoubtedly depend on copepods 

 and phyllopods for food. The stomachs of young pickerel (Esox 

 reticulata) which we examined were filled with the remains of phyl- 

 lopods, while larval lobsters were proved conclusively to prefer 

 copepods and phyllopods to other food. ^lany food fish subsist 

 partially at least on entomostracas, and the appearance of " schools " 

 of fish may depend directly or indirectly on the presence of these 

 Crustacea. The entomostraca, therefore, are one of the most impor- 

 tant links in food supply between the lower plants and animals and 

 the higher animals. 



This list makes no pretence at completeness, but merely brings 

 together all previously recorded species and those identified in the 

 tows taken during a year and a half. Further work could easily 

 enlarge the list, as the entomostracal fauna of the State is very rich 

 and has received but little study. No especial attempt has been 

 made to obtain fresh-water forms, but such as have been identified 

 are included. The marine forms were largely secured by towing 



