192 College of Forestry 



Sphseriidse, were abundant in filamentous algae associated 

 with oligochaete worms, chironomid larvae, amphipods, Cla- 

 docera, etc. They occurred on boulder, sand, clay, and mud 

 bottoms, in 13^-11 feet of water. The largest number was 

 found in Habitat No. cxlix, in 8^^ feet of water, a dredging 

 including 502 individuals. Smaller numbers were found at 

 depths of 9 and 11 feet. 



Subclass Malaccstraca 



order amphipoda 



Family Gammarid^ 



Eucrangonyx gracilis (Smith). Gammarus limneus Smith. 

 Gammarus fasciatus Say. 



Family Orchestiid/E 

 Hyalella knickerbockeri (Bate). 



Of the amphipods, Hyalella is by far the most abundant, 

 greatly exceeding the other species combined (see Tables 

 16-35). It is widely distributed as regards depth, being found 

 in water from one to 15 feet deep. Eucrangonyx gracilis is 

 the rarest species and appears to be confined to water four feet 

 deep or less. The amphipods occur in filamentous algae asso- 

 ciated with other crustaceans and with oligochaete worms and 

 chironomid larvae (see Table No. 47). Identifications by Miss 

 Ada L. Weckel. 



order lsopoda 

 Family Asellid^ 

 Asellus communis Say. 



This little isopod is very abundant in algae associated with 

 other crustaceans, with worms and chironomid larvae, and 

 gastropod mollusks. It is common in water from 1-6 feet 

 deep, is frequent at 8 feet, and rare at 10 feet. It is also rare 

 on boulder and gravel bottoms and is most abundant on clay 

 bottoms in 4-5 feet of water. It is found on all varieties of 

 bottom and its universal presence is due probably to the preva- 



