Occasional Papers of the Museum of Zoology 3 



and large patches of water cress occur on both banks. The 

 Hverwort Riccia fliiitans forms a large part of the floating veg- 

 etation while ]Marchantia is found along the shore. Here mol- 

 lusks are more plentiful than in the preceding stream ; the same 

 profusion of water bugs occurs here, and dragon fly nymphs 

 are even more numerous. 



Aphredoderus is abundant in this lower portion of the 

 stream, living in the cress in company with Umbra limi, 

 Enpomotis gibbosus, Amciunis, sp., Microptenis sahnoidcs, 

 and Eucalia inconstans. It is more loosely associated here 

 with Notropis cormitus, Notemigonns crysolcucas and 

 Pimcphalcs notatus, these species holding to the open water 

 in midstream. Trout have been repeatedly planted in this 

 brook, but none has been found during these investigations. 



Farther upstream, where the surface becomes almost 

 covered by cress and peppermint, x\phredoderus was not 

 found. 



Xot all streams in the immediate vicinity of Black Lake 

 contain pirate perches. In a large deep ditch near Updegrove 

 Lake Aphredoderus is rare, but Enpomotis gibbosus. Microp- 

 terus salmoides, Umbra limi, and Fundnlus notatus are 

 abundant. A stream flowing into Red Lake is too sluggish 

 for Aphredoderus ; Umbra limi swarms beneath its duckweed 

 covered surface. A brook tributary to a stream flowing into 

 Barton Lake abounds with trout (Salvelinus fontinalis), 

 Umbra limi and Esox vcrmiculatus, but Aphredoderus is 

 absent. 



Pirate perches are lowland fishes, in the region studied 

 never being found far from large streams or lakes. They 

 inhabit dense vegetation and avoid open water: over ninety 

 per cent of the manv specimens taken in this locality were 



