SHIRAS EXPEDITIONS TO WHITEFISH POINT. 137 



area, but this coukl not be examined. The l)ottom of the shoal is of 

 hard sand with a tliin layer of humus over it in many places and much 

 vegetation occurs in this shallow water, although irregularly distributed. 

 Partly submerged bulrushes, yellow water lilies, scouring rushes {Equi- 

 ■setiim) form large and conspicuous patches; and along the marshy 

 shore at the west end are rank growths of Sagittaria, cat-tails, and 

 sweet gale, as well as sedges, grasses, and other plants. Under the 

 water are pontl-weeds, bladderworts, tape grass, and water milfoil. 

 Sponges produce conspicuous tufts and incrustation on submerged 

 brush and other objects; some collected were Myenia fluviatilis and 

 Spongilla fragilis. Leeches were common, and two forms were taken, 

 Haemopsis marmoraius and Placobdella rugosa. Some isopods {Man- 

 caseUus tenax) were found. Larvae of May-flies (Heptagenia), some 

 water bugs (Corixa), and a few whirl-i-gig beetles {Gyrinus canadensis) , 

 were the aquatic insects taken. 



The more detailed observations on the fish were made at Station 142 

 (Plate XXVB). Small perch were very abundant here but they stayed 

 about the water lily zone. Good-sized Cayuga minnows were in large 

 schools on the shoal but chiefly on parts where the water lilies were 

 absent and thus not associated closely with the perch. A few small 

 pikes were found in the sweet gale zone along the shore here. One 

 good-sized one (about nineteen inches long) was captured beneath the 

 gale. The species of fish taken at this station were as follows: com- 

 mon perch, Cayuga minnow, spot-tailed minnow, common sucker, 

 common pike, black-sided darter, Johnny darter, and common sculpin. 



In the large marsh area at the west end of the lake and cut through 

 by Shelldrake River, one or two specimens of each of the following 

 were caught: mud minnow, common pike, Johnny darter, and com- 

 mon sculpin. A small crayfish, Cambarus propinquus, was taken here 

 with the fish. 



Shelldrake River. 



A portion of Shelldrake River, about a half mile in length, l}'ing 

 about two miles southeast of Vermilion and about a quarter of a mile 

 above Shelldrake Lake, was examined by wading the entire length, of 

 this portion and dipping with the hand seine in all places likelv to have 

 fish. 



This part of the stream winds through a sAvamp Avith alders, spruces, 

 birches, pines, and other trees, which produce a very dense growth 

 (Plate XXVIA). It averages here i^erhaps thirty feet in Avidth, but in 

 places narroAvs to a feAv feet and Avidens to as much as fifty feet. The 

 Avater is clear, and \''ery free of sediment but stained. The bottom is 

 of hard, firm sand and is bare almost everyAvhere except that it is 



