A HISTORY OF CUMBERLAND 
branchial, while the hinder feet are as in the Ctenopoda. The Onychéd- 
poda, or ‘ nail-footed,’ have only four pairs of feet, these being prehensile, 
ending in strong nails, and having a toothed process at the base. The 
Haplépoda, or ‘ simple-footed,’ are so called because their six pairs of feet 
are simple, without a process.’ All these sections are represented in the 
waters of Cumberland. 
To the Ctenopoda belongs Sida crystallina (O. F. Miiller), of which 
Miss Edith M. Pratt, in her paper on ‘ The Entomostraca of Lake Bassen- 
thwaite,’ reports that ‘it was the most common species taken in April, 
1898. In June very few specimens were taken, but these were of a large 
size, with well-developed ova and embryos.’* ‘This species has a very 
transparent carapace, and a singular apparatus on the back of its head for 
attaching itself to weeds or to other objects such as the wall of an aqua- 
rium. At present it stands alone in the genus Sida, but that genus itself 
is one of a considerable family named after it, the Sidide. Among these 
Sida is easy to recognize, because in its second antennz it alone combines 
a three-jointed dorsal with a two-jointed ventral branch, and it alone has 
a row of twenty or more simple and isolated teeth on the dorsal margin 
of its tail-piece.? In the same family stands ‘Daphnella brachyura,’ which 
Miss Pratt reports as common in lake Bassenthwaite in June but absent 
in April.4 The name Dapédnella, applied by Baird in 1850, was pre- 
occupied, and has therefore to give way to Diaphanoséma, Fischer, 1851, 
and here it will be noticed that the generic name, meaning ‘a diaphanous 
body,’ testifies to the transparency of the valves, just as the specific name 
does for the crystalline Sida. How greatly this character adds to the ease 
and pleasure of studying the living animals under the microscope will be 
understood without any laboured discussion to prove it. In Diaphanosoma 
the tail-piece has no teeth, and the very large second antenne have two 
joints to the dorsal and three to the ventral branch. The species men- 
tioned is far from being confined to lake Bassenthwaite. It can be 
obtained also in the Sea of Galilee and in very many other parts of the 
world. 
The Anomépoda, being by far the largest of the four sections, is 
here as commonly elsewhere the best represented. While the other 
three sections have four families among them, this has four families to 
itself, and within these are distributed a very considerable number of 
genera and species. Of the families, the Daphniide is that which has 
been able to force itself most into notice, so that occasionally members 
of it swim into the ken, not only of scientific students, but of ordinary 
observers. The genus Daphnia, O. F. Miiller, is credited with about a 
hundred species and varieties. But these species and varieties are not all 
credited with being ‘ good ’ in the scientific sense of that much enduring 
epithet. The characters on which they have been founded often prove 
1 Jules Richard, Ann. Sci. Nat., ser. 7, vol. xviii. p. 331. 
2 Ann. Nat. Hist., ser. 7, vol. ii. p. 471 (1898). 
3 J. Richard, Ann. Sci. Nat., ser. 7, vol. xviii. p. 335. On p. 337 the words ventrale and dorsale 
are accidentally transposed. 
4 Ann. Nat. Hist., ser. 7, vol. ii. p. 4.70. 
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