A HISTORY OF CUMBERLAND 
parent crystalline lenses.’ ‘The most striking feature however of this 
Cladoceran is that it possesses an extremely long spine at the end of its 
abdomen, more than twice as long as the rest of the animal itself.” ‘The 
matrix sometimes attains an enormous size, holding as many as from ten 
to twenty embryos at atime. These are readily distinguished by their 
large eyes and long spines which are curled round them.’ ‘The man- 
dibles (fig. 4) are long and are articulated on the shell at the back; they 
curve round the body and meet in front of the mouth. In front they 
have a set of large teeth. Although I have dissected several specimens 
I have altogether failed to find any maxille. I cannot but think how- 
ever that there must be some, although they may be rudimentary.’ 
‘There are two known species of Bythotrephes, B. Cederstrimii and B. 
lJongimanus. ‘The latter has never yet been found in England. These two 
species, together with Po/yphemus, Pleopis and Evadne, form the family 
Polyphemidz.’ ‘Distribution. I found B. Cederstrémii first in Grasmere, 
but subsequently in most of the large lakes in Cumberland and West- 
morland. It lives in the middle of large pieces of water and seems to 
be more abundant in the autumn than the spring.’* 
In passing it may be noted that the family has been augmented 
since Mr. Beck’s paper was published, and that the name Podon, Lillje- 
borg, is now used in preference to its equivalent, P/eopis, Dana. More 
important to our present purpose is Miss Pratt’s record of Bythotrephes 
longimanus, Leydig, of which she observes, ‘ This species has not been 
recorded before from the English lakes. In Bassenthwaite it was very 
rare in April, but very abundant in June, with eggs, embryos, larve and 
young.’*” Miss Pratt calls attention to Beck’s description of the com- 
panion species, but was doubtless unaware that in the interval between 
Beck’s paper and her own Professor G. O. Sars had reduced B. cederstrimii 
to a synonym of B. /ongimanus.2 The differences on which Schédler 
relied were due, it seems, only to the circumstance that he examined 
specimens in good condition, while those which Leydig described and 
figured were extracted from the stomach of a fish, a repository from 
which the naturalist may sometimes obtain prizes, but must expect not 
unfrequently to find them slightly out of repair. 
The Haplopoda, like the Onychopoda, own but a single family, 
namely the Leptodoride. But this family has a special interest, because 
so far as known it is only in its single genus, Leptddora, that the embryos 
hatch in the nauplius stage, other Cladocera passing through this phase 
of existence while still in the egg. Professor S. J. Hickson, F.R.S., 
when initiating the researches in lake Bassenthwaite, evidently felt 
himself partly repaid for his trouble by this very nauplius. He 
says, ‘In April, 1897, when the weather was still very cold and 
blasts of icy wind blew down in gusts from the snow-capped Skiddaw, 
I took a few samples of the Plankton as a preliminary step to further 
1 Fournal of the Royal Microscopical Society, ser. 2, vol. iii. pp. 780-82, pl. xii. figs. 1-8 (1883). 
® Ann. Nat. Hist., ser. 7, vol. ii. p. 472 (1898). 
3 Vid.-Selsk. Forbandlinger, No. 1, p. 51 (1890). 
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