J. M. Thomson. 
64 
There seems little doubt that optimum conditions in the estuary for T. 
cavolinii occur during the summer, probably before March. Males were 
more numerous than females from March through the winter, but females 
were present in greater numbers than the males in December. 
Dactyl opusia tisboides Claus 1863. 
This species was never very common, but was taken in every sample 
from March to July. Distribution is very wide: recorded from Woods Hole, 
Franz Josef Land, Greenland, Coast of Norway, Kiel Bay, British Isles, 
France, Mediterranean, Red Sea, Kerguelen, Western Australia. 
Ectinosoma propinquum T. and A. Scott, 1896. 
Also not common but taken from March to June. Distribution: Scot- 
land, Franz Josef Land, Coast of Norway, Ceylon. 
Harpacticus gracilis Claus, 1863. 
It is possible that some specimens attributed to this species are referable 
to another as each individual was not checked. But several times during 
the year a proportion of the specimens were examined and on each occasion 
proved to be H. gracilis. The limbs correspond perfectly in structure with 
the drawings of Monard (1928). Distribution includes the North Sea, 
Mediterranean, Black Sea, Chilka Lake, Suez Canal, Atlantic Coast of North 
America, Kerguelen. 
The species was evidently decreasing in March, was poorly represented in 
April but underwent a huge increase in May to decrease in collections 
throughout June. It was absent from August to October. In November a 
few specimens occurred, but by December a tremendous increase had again 
taken place. 
MesocJira parva J. M. Thomson. 
This was recorded in sparing numbers throughout the year until October 
when it swarmed in the shallower waters, while Gladiof evens imparipes was 
predominant rather deeper. A check of the collection has shown that while 
the October-November increase included only M. parva earlier in the year 
(March- June) a few of the specimens recorded as M. parva are referable 
to another species, and are tentatively assigned to M. pygmaea (Claus) with 
which they agree most closely. This latter was represented by only a few 
specimens among the total. No sign of M. parva was found in December, 
its place being taken, apparently, by Harpacticus gracilis . 
It is noteworthy that the proportion of males to females was 1 : 1.6 in 
October but was only 1 : 6.8 in November. About 50% of the females were 
ovigerous. 
Perissocope sp. (?) This is a very uncertain identification, being 
first made from Wilson’s key (1932), but imperfectly confirmed. 
