1130 Proceedings of Royal Society of Edinburgh. [sess. 
Synch ceta neglecta , Zaeh. 
It is a well-known fact that the different species of the genus 
Synchceta can hardly he distinguished by means of preserved 
material ; when the water with the living animals is immediately 
poured out into glasses containing concentrated formaline, it some- 
times happens that the animals do not pull in their wheel organ. 
In the samples I have found a few specimens with protruded wheel 
organ ; on the basis of these samples I suppose that the species 
in the pelagic region of the lake is S. neglecta (Zach.). It is doubt- 
less perennial, and its max. seems to occur at a low tp. 
Ploesoma lenticulare , Herrick. 
In the two samples of 15th and 30th September I have found 
a species of Ploesoma . The animal was rare ; the lorica of the 
animal lacked the fluffy tissue characteristic of the two species 
P. Hudson i (Imh.) and P. molle (Kellicott.) It differed from 
the easily recognisable P. triacanthum (Bergend.). Still, I am 
not sure whether I had the P. lenticulare (Herrick) or P. 
truncatum (Levander) to deal with, as all of the animals were 
greatly contracted. In all the samples from August to September 
I found the limnetic egg characterised by a great hyaline space 
between the very small yolk mass and the egg-shell. 
Asplanchna priodonta, Gosse. 
This species has occurred in very few samples at different times 
of the year. I believe it to be perennial, but it seems rare in the , 
pelagic region of the lake. 
Anur cea cochlearis , Gosse. 
The species is found in all the samples and is therefore un- 
doubtedly perennial; I have not observed any strongly marked 
max. The number of specimens is never great ; perhaps a small 
max. may be pointed out for October and November. All the 
individuals belong to the well-marked hyaline, long-spined lake 
form. 
