149 



absence at Yarnelle's landing may probably be accounted for by the sud- 

 den slope at that shore and by the gravelly beach. Whenever long bars 

 run out into the lake. S. 1acitf:tris marks the place by projecting out into 

 long capes. Fig. 4 represents a characteristic patch of <^'. lacustris (south 

 of Chicago Hill pier), along with other relations. On the left, shorc^ with 

 willows, and mud liar with Scirpiis stniis. Between the shore and Scirpus 

 are patches of Piiiitcdci'id cordatd. 



Fig. 4. 



PotiiiHoi/ifnii [n vt'DKitiis forms a wide licit extending from rather shallow 

 water (four feeti to seven or eight feet. It occurs in scattered patches all 

 round the lake. P. (iinplifoUiis grows in somewliat 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. MijriophiiJluiu and Crratophi/Uiim generally g-ow 

 in the same dejith of water and often form mixed patches. The latter Ls 

 found almost all round the lake in considerable quantities. These two 

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



Pof(iiiHj(/rf(tti ]iic( NX. though abundant, is rather scattered. /'. zo^t raefo- 

 liiis and H<i< nnitlirni iJiiliia grow intermixed in about five feet of water. 



