474 Wisconsin Academy of Sciences, Arts, and Letters. 
Table 5. Numerical distribution of various forms of animals 
between the shore line and a depth of 7 meters. 
The averages are computed on a basis of 50 stations for each 
of the depths given. The total number of individuals of the 
various forms may be ascertained by multiplying the averages 
by the areas at the different depths, viz., 0—1 m. = 4 sq. km.; 
1-2 m. and 2-3 m. = 1.7 sq. km. each; 3-5 m. = 3 sq. km.; 5-7 
= 2.5 sq. km. 
Name 
0-1 m: 
Platyhelmia 
Planaria maculata. 
-Polycells nigra. 
Dendrocoelium lacteum 
Mesostoma ehrenbergii., 
64.00 
0.26 
0.26 
N emathelmia 
Gordius aquaticus 
Pi nk Nematode..., 
2.33 
0.95 
Chaetopoda 
Small Oligochaeta. 
Sparganophilus eiseni. 
Lumbriculus limosa. 
Lumbriculid sp—... 
Tubifex tubifex. 
Limnodrilus claparedianus 
169.00 
0.44 
3 11 
2.88 
Hirudinea 
Leeches. 
11.2 
Mollusca 
Amnicola limosa 
2.21 
Ancylus. 
Limnaea stagnalis. 
Physa ancillaris. 
Physa heterostropha. 
Physa gyrina. 
Planorbis bicarinatus.... 
Planorbis campanulatus. 
Planorbis parvus. 
Pleurocera elevatum.... 
Campeloma... 
Valvata tricarinata. 
Sphaerium. 
Anodonta & Lampsilis.. 
Corneocyclas. 
2.44 
0.11 
2.66 
4.57 
2.84 
1.97 
3.57 
0.40 
0 22 
0.06 
1.13 
Crustacea 
Dikerogammarus fasaiatus 
Hyalella azteca.. 
Cambarus propinquus.. 
Hydraehnida 
Atacinae.. — 
Arrhenurinae..... 
Pioninae.... 
Lebertilnae..... 
Limnesiinae.... 
22.9 
150.4 
1.37 
2.28 
8.64 
4.64 
0.1 
30.9 
Averages per sq. m. at depths of 
1-2 m; 
2-3 m: 
3-5 m: 
5-7 m: 
3.77 
8.97 
54.10 
18.50 
0.13 
0.35 
0.92 
0.07 
267.00 
637.00 
1560.00 
610.00 
0.66 
3.55 
0.21 
0.13 
0.22 
9.55 
8.00 
0.33 
0.44 
10.00 
1.93 
0.75 
14.0 
0.25 
118.00 
168.7 
200.00 
129.00 
0.06 
0.26 
0.91 
0.55 
1.00 
1.50 
1.05 
2.00 
0.11 
0.40 
3.13 
60.60 
14 60 
ii.io 
0.77 
3.82 
33.40 
75.40 
0.68 
1.77 
5.00 
21.70 
9.11 
4.77 
15.20 
33.70 
1.02 
1.00 
1.65 
1.25 
0.55 
0.33 
4.56 
20.50 
1.86 
3.62 
0.15 
2.54 
1.73 
3.47 
3.30 
0.13 
0.13 
0.04 
1.35 
19.50 
0 6 
76.7 
88.5 
286.5 
82.7 
12.6 
15.60 
3.04 
12.8 
20.6 
20.6 
is .2 
4.0 
11.5 
2.13 
0.5 
0.97 
2.28 
48.7 ] 
50.3 
87.6 
20.7 
