No. 628] HABITAT RESPONSES OF WATER-STRIDER 407 



bank, it began to jump downstream. This continued for a 

 distance of two yards, when it turned, facing- the right 

 bank of tlie stream, and jumped in that direction for one 

 yard until it reached the middle of the brook channel, 

 '^riio gorrid again turned to the left, this position directing 

 its head downstream, in which general direction it con- 

 tinued to travel, until after a number of stoi)s, it even- 

 tually rcnclicd tlic large pool. Tu iiassing ovci- its entire 



route, this ^ 



It ]in> hccii stated that live gcrri.l> \v;iiidriv,l toward 

 the right l)aiik of the brook, on tii'st leaving tlie >ite of the 

 former ]iool. Three of these turned toward the middle of 

 the stream channel and jumped upstream for two yards, 

 turning to the left, they moved toward the bank of the 

 brook. On reaching it, first one and then the others 

 jumped downstream. After a number of pauses and 

 deviations to the right and left, two of them again turned 

 w^tli their heads directed ui>stream and continued to jump 

 and walk in that general direction. After several ei-ratic 

 movements and two sto|». the third ucri-id turned up- 

 stream. The insect jumped in this diivction for thice 



Wlirn the inserts were llotie.'d last, they had ti'aveh.l 

 eiglil.M.n yanU upstream awa> from th.- ^ito of th.' fMian..i 

 pool, from which th.'N oi-iuinally cam.'. ( )ne ..f theni had 

 crawh.l mu\rv a i-i.-cr of ,lriflwo..d and iiad l.r.n th.'r.' 

 for thirty minutes wh.-n 1 di>conlinned my ohscrvations. 

 These gorrids were sought carefullx- the following day, 

 but 1 was unable to tind them. 



