No. 628] HABITAT RESPONSES OF WATER-STEIDER 403 



low at siieli times, and tliat llu^v ri'<'(|U('?itlv sook dry situa- 

 tions. Tlie subjoci ..f lill)cniati(Mi will lie discussed at 

 2:reater lensrth in aiioiiM'i- papci-. 1 iiia\ sav. however, 

 that tho^e uator id. do imt hd. i„.nr ,,, .nix of tho 

 situations iin^nl kukmI the \vnt<T> (|U(iicd, fxccid under 

 thebank«^..f MM.ini^ ,u,d 1 1,, ii ax\ a ^ M .-in lli.' u ,ih i Tlio 

 positive thiu-tnotactic n^-iK.iix- ol tlicsc uciTid- liax .' Ix'on 

 observed fre(|uontlv (hiniiii- pcrioiU ol iiibci-iiai inn. At 

 such times they foruuMl taiiul('(l ma>M'>. winch wt-r.' due to 

 the water-striders crowd iim- clo-cK- load licr. 'I lic-c tacts 

 were recorded in itiv field mncs ;i> carlv as liic winter of 

 1912-191:5. It 1^ iht.n^iiim !n ,<eall that K-en])org 

 (1915;p)). .'.'.I?. 4()i») lia> <)l>MT\e<| >iiiiilar i'esi)onses in the 

 case of Gen- IS m lm Stnl. 



4. Initial i; V'""- ^ J),u ni /hnnL- Witli rofer- 



Wliite Hcatli. it apiK'ared a- if tlie uvrrid^ uii-lit die ri-ht 

 where they were, tor im iii<.\ eiiieiiN occun-ed t<»r apuroxi- 

 mately ten minute^ alter iiie water iiad di-appeai'ed. 

 Soon they began to inex-e awa\. I eaii iidt >l;ite abso- 

 lutely what was the stiiiiiilu.-^ that caa.M'd the initial loco- 



a])pearaii<-e o\' all iii..i>tiire. as this wa- the ciilv evident 

 cli.niLi.' Ml the . M. mal M.nditinn^ SmuU and ,n ^-iiall 

 -nnip^ thev pimped .Mid u.i k< d in an iiim.iinK t.i^hion 

 fnaii the mP nt the PoinM pnn| \\h,h. ,, ,h.„t 

 tliat the wat.a-t riders were le-.^ a<-eu>tMnH.d to h-eoino- 



tion ..n the land tlnm thev were p. h.<-nniotinn cm the 

 %\<U(M. xet theN n„lde f.lllU uoe.l pM.m,... .d-.n^ il h^d 

 of tlK' stream. 



tlic surfaee of .a p..nl in a Mreani. .m frnm .■,„ ;Hpiariiiin, 

 where the\ had he, n ot m . .iptn itv. .ui.l pi. u-ed on the 

 ground or on x.me ether -did Hii fa.-e that thcv at once 



