149 



absence at Yanielle's laiKliiig may probably be aecdiiiited for by the ^sud- 

 deii slope at that shore and by the gravelly lieach. Whenever long- Ivars 

 run out into the lake. .S'. hicustris marks the plaee by projecting out into 

 long capes. Fig. 4 represents a characteristic patch of >S'. lacustri.s (south 

 of Chicago Hill pieri. along with other relations. On the left, shor>^ with 

 willows, and mud bar with Svirijiis stems. Between the shore and Scirpus 

 are patches of rmifcdn-iii corddta. 



Fig. 4. 



Potdiiioi/i fun iKitiiKifiis forms a wide licit extending from rather shallow 

 water ifour feet) to seven or eiglit feet. It occurs in siattered patches all 

 round the lake. P. (niiiilifoliits grows in somewhat deeper water than the 

 preceding. It forms several large patches, one in front of the laboratories 

 and one near the mouth of Clear Creek. Other smaller patches are dis- 

 tributed quite generally. .Mi/riophi/Uuni and CrnitophijUum generally g"ow 

 in the same depth of water and often form mixed patches. The latter is- 

 found almost all round the lake in considerable (juantities. These two 

 plants form their thickest patches in the mud near the outlet. 



Potdmoi/efoii liicriis. though al)undant. is rather scattered. /'. zost racfo- 

 //»x and }l(i<r(inth(i(i iliihia glow intci'mixed iu about tive feet of water. 



