The Fauna of the Algal Zone of the Swan River Estuary. 65 
Tisbe spp. 
Three species of lisbe were identified, none being* particularly numer- 
ous ^except T. ten-era in December. T. tenera Sars and T. fur oat a Baird 
(1850) were found and a third species somewhat questioningly identified as 
T. graciloides Sars. These latter corresponded fairly well with Sars’ figures 
►especially in the detail of the first antennae. 
The three species were present in greatest numbers in December. Their 
numbers during the rest of the year were low, though in July they were 
among the more conspicuous members of the fauna, since all species had 
either disappeared or were present in small numbers. Ovigerous females and 
immature specimens were common in December. 
Distribution : T. tenera : coast of Norway, English Channel, Roscoff, 
Suez Canal, Nicobar Is. 
T. furcata : Alaska, New Zealand, Pacific Islands, Ceylon, Chilka Lake, 
Red Sea, Mediterranean, North Atlantic, Baltic, Nicobar Is., Maidive Is. 
T. graciloicles : West coast of Norway. 
'Gladiof erens imparipes J. M. Thomson. 
The genus is a southern hemisphere one closely related to Boekella. Its 
recorded distribution is from Western Australia through South Australia 
and New South Wales to New Zealand, generally in brackish waters. 
G. imparipes first appeared in July when the river was becoming fresh, 
and slowly increased in numbers to become a dominant form in August, 
and reached its greatest numbers at the beginning of November, though at 
this time it was no longer found in the shallowest water as formerly but 
■only amongst the algae at depths greater than 2 feet. By December only 
•a few specimens remained. 
Males and females were present in approximately equal numbers till 
the November increase, when females were more than twice as abundant as 
males. The proportion of ovigerous females was rather steady at about *4 
•of the total. 
Xestolebris aurantia Baird 1850. 
The peculiarities of this genus left little doubt as to the generic identity 
■of this form. On the basis of its close agreement with Sars (1921) descrip- 
tion of aurantia it has been assigned to that species. Distribution: The 
British Isles, Holland, Baltic, Norway. 
Crurantkura simplicia J. M. Thomson. 
This was taken in few numbers in June, July and September, on 
each occasion on Cysiophyllum only. 
Munna brevicornis J. M. Thomson. 
Taken in July, October, November and December. Numbers were small, 
but several ovigerous females were taken, together with males and immature 
specimens. 
