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ANIMAL COMMUNITIES OF STREAMS 



47 



' 



50 



53 



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Representative Animals of a Rapids Community 



Fig. 47. — An adult brook beetle (Parnidae); twice natural size (original). 



Figs. 48-50. — Different views of the nymph and adult of the May-fly (Siphlurus 

 alter natiis)] 2,2 times natural size (after Needham). 



Fig. 51. — The eggs of a tabanid fly taken from a protruding stone; twice 

 natural size (original). Fig. 52. — Adult fly. 



Fig. 53. — A water-strider (Rhagovelia collaris), from the margin of the swift 

 brook (New Lenox, Gaugars) ; twice natural size. 



Fig. 54. — The common river snail (Goniobasis livescens), covered with calcium 

 carbonate secreted by algae; natural size (original). 



Fig. 55. — An intermittent stream sowbug (Asellus communis); twice natural 

 size (original). 



