The Fauna of the Algal Zone of the Swan River Estuary. 71 
TABLE 2. 
VARIATION IN POPULATION WITH DEPTH. 
Species. 
March. 
July. 
November. 
Enteromorph 
a compressa. 
Cystophyllum 
muricatum 
Ectocarpus 
confervoides . 
Open. 
Sheltered. 
Above 
1ft. 
Below 
1ft. 
A bove 
; 1 ft. 
Below 
1ft. 
Above 
4 in. 
4 in. to 
1 ft. 6in. 
1 ft. 6 in. 
to 
2 ft. 6 in. 
Above 
4 in. 
Leptoplana spp. ... 
3 
1 
5 
Nematoda spp. .. 
32 
8 
10 
12 
Ceratonereis erythraeensis 
19 
4 
5 
•> 
2 
Nereis oxypoda .... 
3 
a 
Small Nereids 
3 
1 
3 
Odontosyllis fidgarans 
2 
Spionids .... 
7 
2 
Ameiro minor 
16 
8 
Amphiascus sp. .. 
10 
9 
Dactylopusia tisboides 
9 
2 
4 
Harpacticus gracilis 
8 
64 
46 
2 
5 
3 
Mesochra parva .. 
5 
804 
33 
Parathalestris sp. 
2 
5 
Tegastes sp. 
1 
Tisbe graciloides ... 
5 
Tisbe tenera 
3 
Zans sp. ? 
3 
1 
Gladioferens imparipes .. 
3 
298 
Xestolebris aurantia 
2 
2 
Cytherid sp. 
1 
3 
2 
Tanais cavolinii ... 
20 
33 
169 
18 
3 
39 
1 
Cruranthura simplicia .... 
1 
4 
Munna brevicornis 
2, 
Caprella spp. 
43 
23 
4 
84 
15 
47 
Corophium minor 
1 
24 
12 
3 
4 
Erichthonius pugnax 
9 
Melita sp. 
3 
8 
15 
Chironomid larvae 
2 
1 
2 
1 
Litarachna 
6 
Modiolus sp. 
2 
1 
Halicarcinus australis 
1 
Ascidea malaca .... 
6 
Botryllus sp 
M 
Total Population .... 
95 
147 
284 
201 
24 
167 
821 
350 
Species Density 
. 
3 I 
16 
8 
16 
6 
18 
7 
10 
M = Masses. 
