88 College of Forestry 
Borrom: Sandy silttomud. Warer: 3 to 10 feet deep. 
VecEeration: All submerged. 
Clasping-leaved Pond-weed (Pota- Water Weed (Hlodea canadensis). 
mogeton perfoliatus) . Hornwort (Ceratophyllum — de- 
Various-leaved Pond-weed (Pota- mersum). 
mogeton heterophyllus).  ° Water Milfoil, (Mzyriophyllum spi- 
Water Celery (Vallisneria  spir- catum). 
alis). Stonewort (Chara species). 
ANIMAL LIFE. 
MOLLUSCA. 
Bythinia tentaculata, very abun- Planorbis »arvus, rare. 
dant. Physa anc. llaria warreniand, 
Valvata bicarinata normadis, rare. young, abundant. 
Planorbis campanulatus, common. <Ancylus parallelus, not common. 
CRUSTACEA. 
Amphipod (Gammarus fasciatus), abundant. 
INSECTA, 
Caddis-fly larve (Oecetis resur-  Caddis-fly cases (Leptocella spe- 
gens). cles). 
Caddis-fly larvee (Polycentropid). Damsel-fly nymph (Hnallagma spe- 
cies). 
Bythina tentaculata is six times as abundant as all the 
wther species combined. <A single plant of Hlodea canadensis 
contained 25 individuals, young and old, of this species. If 
this ratio holds good for a large area a square yard of plants 
would sustain about 1,326 individuals and an acre would con- 
tain the enormous number of 8,503,320. From this estima- 
tion it may readily be seen that an enormous amount of mol- 
lusean life is present in the submerged vegetation of the lake. 
In 5 feet of water two species of clams were obtained with 
the crowfoot dredge (Field No. 257). 
Margaritana margaritifera. Lampsilis borealis. 
Station XL.. Bie Bay (Frextp Nos. 272, 273). Fira. 31. 
Dredgings were made in lines as follows: One-eighth mile 
from shore off Milton Point to near end of Big Bay; thence 
