146 



BULLETIN OF THE BUREAU OF FISHERIES 



was ascertained before and. after straining in order to obtain some information as 

 to the relative amount of coarse organic debris, 'pieces of plants, chips of wood, and 

 in some instances garbage, gravel, and fine mud. The partial results of these deter- 

 minations are shown in Table 6. 



RESULTS AND DISCUSSION 



The abundance of the bottom-dwelling animals is expressed in numbers per 

 square yard, and the data are shown in Table 5. The table shows that there is a 

 marked difference in the kinds and numbers of animals that occur at the different 

 stations. 



Table 5. — Bottom fauna, animals -per square yard, 1926 

 , [S=shore; C=charrael] 



Bottom fauna 



Sta. 1, 

 Aug. 14 



Sta. 1, 

 Sept. 7 



Sta. 2, 

 Aug. 14 



Sta. 2, 

 Sept. 7 



Biology 

 Bldg., 

 Sept. 10 



Lake 

 St. 

 Bridge, 

 Sept. 13 



Sta. 3, 

 Sept. 8 



Sta. 3, 

 Sept. 8 



On 

 stones 

 Sta. 3, 

 Sept. 8 



Sta. 4, 

 Aug. 17 



Sta. 

 6-S, 

 Aug. 17 



Dragon fly nymphs 



36 























May fly nvmphs 



144 

 72 

 396 





















Caddis fly larva; 























Simulium ._ 























Tubificidae 



252 

 36 

 36 





15, 120 



364, 000 



118, 000 



10, 800 



632 

 36 



i 6, 159 



5 



108 



11, 970 

 144 



Chironomus 



108 I 36 



Hyalella _ _-_ -._ 













Planaria _ 



72 





















Campeloma rufum. 







1, 600 

















Sphrerium sp 



108 





















S. notatum 







54 

















MuscuKum near transversum 













85 









1,620 



M. near trunoatum 













500 



72 









Musculium sp 























Beetle larvae . 



72 





















Leeches 











72 





14 



1 

























Bottom fauna 



Sta. 

 5-S, 

 Sept. 15 



Jackson 

 Street 

 Bridge, 

 Sept. 27 



Sta. 

 6-S, 

 Aug. 18 



Lefts 

 Sta.' 

 6-S, 

 Sept. 16 



Rights 

 Sta. ' 

 6-sj 



Sept. 16 



Sta. 

 7-8, 

 Aug. 18 



Sta. 

 7-S, 

 Sept. 16 



Sta. 

 7-0, 

 Aug. 18 



Sta. 

 7-C, 

 Sept. 16 



On 

 stones 

 Sta. 8' 

 Aug. 19 



Sta. 8 



UO^Ji.. J.U 



May flv nymphs _ 





















(') 



72 

 360 



Tubifieidse 



5,832 

 3, 240 



2,880 

 144 



2,520 



75, 400 



10, 260 



103, 860 



126, 000 



31,680 



65, 400 



Chironomus 





Hyalella 



















3, 240 

 432 



Planaria 























Pleurocera acuta 





















9 

 11 

 1 



r>l.U8 Zl 



Physa sp..._- 























Campeloma rufum 





















36 



Heliosoma trivolvis... 









































18 

 167 



Leeches 



1, 157 



36 













720 























Bottom fauna 



Sta. 

 9-S, 

 Aug. 27 



Sta. 

 9-S, 

 Sept. 17 



Sta. 

 9-C, 

 Aug. 27 



Sta. 

 9-C, 

 Sept. 17 



Sta. 

 10, 

 Aug. 27 



Sta. 



u-s, 



Aug. 28 



Sta. 

 11-S, 

 Sept. 18 



Sta. 

 11-C, 

 Aug. 28 



Sta. 

 11-C, 

 Sept. 18 



Sta. 

 14-S, 

 Aug. 31 



Sta. 

 14-S, 

 Sept. 19 



Dragon fly nymphs 





48 





48 





18 

 54 



12 

 12 











Damsel fly nymphs 













36 

 144 





May fly nymphs 











( s ) 







342 



Caddis fly larvas 









12 

 240 











Tubificida? 



1, 980 

 18 



1, 260 

 54 



2, 900 



36 









18 

 36 

 18 

 18 

 36 

 90 



900 





180 



Chironomus 





54 

 3, 600 



36 

 3, 200 



684 

 144 



Hyalella... 



3,000 





24 









Assllus 











Planaria 











36 

 90 











Pleurocera acuta 













18 



18 







Campeloma integrum 



252 



288 

 48 



108 



72 





36 



18 



Anodonta imbecillis 













Musculium near transversum 







2,520 

















M. transversum 



1, 600 

 90 

 2,295 





















Heliosoma trivolvis 

























1, 776 



684 



492 







12 



180 





36 















! Per liter. J Many. • Some. 



