CRUSTACEANS 
investigations. The material I then obtained proved to be of con- 
siderable interest, containing among other things the interesting 
Nauplius \arve of Leptodora.”’ Of the species Leptodora hyalina, Lillje- 
borg, Miss Pratt says, ‘In April only the larve and very young forms 
were taken, chiefly at the surface, in Bassenthwaite. In June this species 
was exceedingly abundant, with eggs, embryos, and young, but no young 
larve were taken. It was moreover confined to the middle of the lake, 
where the water is deep (see map, p. 475). Very few mature specimens 
were taken at the surface or at the depth of 2 feet to 4 feet, but from 
6 feet to 10 feet (10 feet=greatest depths at which tow-nettings were 
taken) it was taken in great quantities.’ An examination of the adult 
animal will show several points which if not absolutely peculiar are 
shared with but few other species, such as the large number of sete on 
the second antennz, the acuteness of the mandibles, and the great length 
of the tract of the body between the last pair of feet and the two dorsal 
sete of the abdomen. 
The Ostracoda are readily distinguished from the Cladocera by the 
fact that instead of having the head distinct they keep that part in 
common with the rest of the body sheltered within their two mollusc- 
like valves. They no doubt occupy the waters of Cumberland in accus- 
tomed variety and abundance, but the only record I have come across is 
one which reports Cypris obliqua, Brady, from Derwentwater on the 
authority of the late David Robertson, LL.D.’ 
The Copepoda have received more attention. These by their dis- 
tinctly segmented body and the absence of enclosing valves wear a much 
more appreciably shrimp-like aspect than the groups already discussed. 
Dr. G. S. Brady has recorded five species as belonging to this county, 
and Miss Pratt has recorded eleven species of which two only are 
common to Dr. Brady’s list, the two lists combined thus producing a 
total of fourteen species, which after certain necessary modifications 
becomes thirteen species and one variety. This may be regarded for the 
time as a respectable assemblage, but Mr. D. J. Scourfield in 1897 
reckons the known British freshwater Copepoda at fifty-four, so that the 
percentage from Cumberland will easily admit of being greatly raised in 
the future. 
Most of the species to be mentioned belong to the family Cyclopide 
and to the well-known freshwater genus Cyc/ops, O. F. Miiller, of which 
the species are tolerably numerous, but, as M. Canu observes, differing by 
characters of feeble intensity. It is impossible here to enter into all the 
minute details by which they are discriminated, for which reference must 
be made to such works as Dr. Brady’s Monograph of the British Copepoda, 
published by the Ray Society (1878-80), and the more recent German 
treatise by Dr. Otto Schmeil, published in the Bib/iotheca Zoologica 
(1892-96). 
Of Cyclops gigas, Claus, Dr. Brady says, ‘I have found it plentifully in 
1 Ann, Nat. Hist., ser. 7, vol. ii. p. 468. 2 Loc. cit. p. 471. 
3 Brady and Norman, Trans. R. Dublin Soc., ser. 2, vol. iv. p. 77 (1889). 
165 
