OF THE ENGLISH LAKE DISTRICT. 
439 
(3) Median seta of the furcal rami of nuusual length. 
(4) Outer seta of the fiirca of half [crinitus) * or scarcely more than half 
(venushis) the length of the inner seta. 
(5) Swimming-legs with the same spine- and seta-formiila j — a formula 
only found otherwise in C. capillatus, Sars. 
G-raeter states that the abdominal segments are jagged and tliat the surface 
of the cuticle is pitted over the whole body, but I have not been able to see 
this in the specimen, owing, no doubt, to its transparency. 
Since Graeter's name is later than that of Norman and Scott, I have 
therefore regarded it as a synonym of C. venustiis. 
It is evident that this species and C. viridis are very closely related, as has 
already been pointed out both by Graeter and by Chappuis, but they are 
certainly distinct. 
This species was found to be not uncommon in Sphagnum pools near 
Greendale Tarn and on Floutern Pass. 
Table 9. — Showing spines and setse on last joint of the exopodite 
in species of the C. viridis-group. 
Leo-l 
Cyclops venustus, Norm. &. Scott 
„ crinitus, Graeter 
., viridis, Fischer 
,, capiUnhis, Sai's 
., vernalis, Fischer 
,, vernalis var 
,, rohiistus, Sars 
SiDA CRYSTALLINA, 0. F. Mliell. 
S. crystallina is a littoral species not properly, or at least generally, 
belonoing to the plankton, though frequently recorded as occurring in open 
water. In the Lake of Geneva, Lake Como, Lake Maggiore, and other 
* In the specimen which I have examined this seta is more than half the length of the 
inner seta, and so agrees completely with C. venustus. 
t In the specimen at my disposal it is impossible to count the spines and seise with 
certainty on all legs. I have given in the table only those which were beyond doubt. 
