520 



Alongshore July and August collections, in 191 1, were similar to 

 those at Morris, consisting mainly of Sphccrotilus natans, rather 

 less abundant than above, and Stigeocloiiiuiii tcnuc, found only in 

 shallow protected places. Here also were back-swimmers {Notonec- 

 tidcu), a few Chironomus larvae, and miscellaneous oligochaete worms. 

 A few crawfishes were captured inside or near the mouths of creeks. 

 No Unios were seen here, either dead or alive; but a small bivalve 

 mollusk (Sphccriuiii transversiim) was abundant in protected pockets 

 along the north shore in water six inches to a foot deep, and a few 

 living specimens of Physa, Lymncca, and Planorhis were taken in 

 similar situations. The bottom sludge contained at this time the 

 same slime worms {Tuhificidcc) as were found at Morris, as many 

 as fifty per plate near the south shore in October, 19 12. 



In August and October, 19 12, our more extensive collections gave 

 us a larger list of species, of w'hich only the most significant will 

 be mentioned here. Besides the septic SphcurotUiis, Carchcsium, and 

 Bpistylis, which were less prominent than above, but still everywhere 

 abundant, there were, at Marseilles the three blue-green algas, Lyng- 

 bya versicolor, Oscillatorio limosa, and Phormidium unciuatuvi, the 

 two latter of which are classed as pollutional and contaminate, re- 

 spectively. The filamentous algse most frequently obtained along 

 shore were species of Stigeoclomum, Cladophora, Spirogyra, and 

 Ulothrix, mentioned in the order of their abundance in our collec- 

 tions. 



The organisms of the sludge, were, of course, the same as those 

 of the preceding year. A marked difference was noticed between 

 the chutes on the opposite sides of the island which divides the river 

 a short distance above the falls. The current in the south chute 

 is relatively weak, and the bottom sediments here were fine, light, 

 and full of sludge worms; while in the strong current of the north 

 chute the silt was denser and darker, with few or no Tubifex. Oli- 

 gochaete worms, including naiid species, w-ere found also in the ooze 

 along shore, especially abundant among growths of the blue-green 

 alga Lyngbya. Leeches were only occasional. There were no shore 

 or bottom crustaceans seen at Marseilles except certain species of 

 Cyclops, abundant among alg?e and duckweed along the margin of 

 the river, and a few crawfishes found only at or within the mouth 

 of a small tributary creek. Our collections of adult insects made at 

 this place represent fourteen genera, but the larvae, except those of 

 mosquitoes and horse-flies (Tabanid(u), found each in but one col- 

 lection, were those of Chironomus. Both blood-red and yellow spe- 

 cies with pupae and unhatched eggs were obtained in twenty-one 

 collections. No living Unios were secured either above or below the 



