The Fauna of the Algal Zone of the Swan River Estuary. 63 
NOTES ON THE CHIEF SPECIES. 
The notes presented below are mainly of an ecologic and systematic, 
nature. No detailed account of any species is given. 
Lep topi an a sp p . 
A few specimens were definitely identified as Lept-o plana , but it is pos- 
sible that other genera are included under this heading. These animals- 
were much more common on the rocky substratum, and occurred on the algae 
mostly when they were covered in diatoms and were in an old and semi- 
decaying state. 
Ceratonereis erythraeensis Fauvel 1919 and Nereis oxypoda Marenzeller 
1879. 
Monro (1938) has recorded these species from the Swan estuary, and 
Augener (1913) named ? Nereis ( Ceratonereis ) aequisetis which Monro says 
may be the former species. These were the largest and most common of' 
the nereids found on the algae. 
Nereis albanyensis Augener 1913. 
A few specimens were obtained in August. The species has been re- 
corded by Augener from Albany and Fremantle. Except for an occasional 
small specimen, Nereids were absent from March to October. 
Tanais cavolinii Milne-Edwards, 1828. 
This is probably a cosmopolitan species. It has been recorded from 
the Atlantic Coast of North America, Bermuda, Greenland, M est Coast of 
Norway, British Isles, Western France, Azores, Mediterranean. It usually 
occurs in shallow water (lft. to 6ft.) among algae. It has also been 
recorded from oysters, on B alarms , on Pinna , and sponges. 
T . cavolinii is tubicolous, though it leaves its tube quite regularly in 
search of food and crawls slowly over the algae. The tube is of mucin, to 
which little bits of algae and other detritus are joined. On several occasions 
Nematodes were found in the same tube. The tubes are usually twice as 
long as the animal, but may be smaller or larger. 
Although as far as ascertained not previously recorded from the southern 
hemisphere, there is little doubt that the species recorded is 1 . cavolinii ~ 
It agrees perfectly with Sars’ (1899) description of tomentosus (synonymy,, 
see Dollfuss, 1897) and with Richardson's (1905) description. 
The numbers of T. cavolinii were greatest in March, and the propor- 
tion of ovigerous females was also greatest at this time (33%). Numbers- 
fell oft* rapidly till June, presumably as a result of the lowering of salinity. 
A temporary increase occurred in early June, ovigerous females being taken* 
for the first time since the end of April. However, by the middle of July 
the species was again very scarce and was not recorded at all in October. 
No females were found from the middle of July to the beginning of 
September. The few specimens found in November were all immature. 
