CRUSTACEANS 
to be so provokingly variable that the new names which they have lured 
authors into inventing for their specification eventually only confuse the 
story instead of helping to unravel the plot. When the same name may 
easily be applied to two or more forms really though not obviously dis- 
tinct, or a single species may be called unwittingly by several different 
names, local records are inevitably exposed to some indefiniteness. The 
“common water-flea’ is Daphnia pulex (Linn.), or D. pulex, de Geer, or 
D. pulex, Latreille, or D. pulex, Baird, or D. pulex, Leydig, or D. pulex 
of a great many other authorities. But, according to Dr. Jules Richard, 
Leydig was the first to give such a description as can be depended upon 
for isolating the form he was describing. Miss Pratt reports from lake 
Bassenthwaite ‘ Daphnia pulex, Latreille,’ and remarks upon it that ‘ this 
species, while being widely distributed in pools and ditches in Britain, 
occurs but rarely in large sheets of water ; it was very rare in Bassen- 
thwaite in April and no specimens were taken in June.’* A reference 
is added to Baird’s British Entomostraca, but the number of the plate is 
unluckily misprinted. The name of Latreille is of no assistance, as he — 
did not contribute any first-hand information to this particular subject. 
Of a nearly allied species, Daphnia obtusa, Kurz, Dr. G. S. Brady states 
that he has ‘ found it in a shallow pool on the line of the Roman wall 
near Garthside, Walton, Cumberland (July, 1897),’ andin his account of 
Daphnia propinqua, G. O. Sars, which he agrees with Richard in regard- 
ing as a variety of Daphnia obtusa, he says, ‘In the summer of 1897, in a 
shallow pool by the side of the Irthing at Walton, Cumberland, I took 
many specimens, all of them immature, which seem to be referable either 
to obtusa or its variety.’” This variety was reared by Sars out of dried 
mud sent from the Cape of Good Hope, and its propinquity to Daphnia 
obtusa is so close that Dr. Richard apparently upholds it more out of 
respect to the distinction of its author than for any other distinction. 
Even in regard to the original D. obtusa he observes, ‘ Like D. pulex, this 
species does not always appear identical with itself ; the variations may 
be tolerably extensive. Many authors even consider D. obtusa to bea 
variety of D. pul/ex, and it is certain that it has often been mentioned 
under the latter name.’* As to its geographical distribution he declares 
that it appears to be much more common than D. pulex, and that probably 
a great number of the localities attributed to the latter ought to be re- 
ferred to the former.* Of Daphnia longispina Miss Pratt says, ‘This 
species was taken by Beck in the English lakes and by Scott in some of 
the Scottish lochs. It was rare [in Bassenthwaite] in April and no speci- 
mens were taken in June.’® No author’s name is given for the species, 
but a reference to ‘ Daphnia longispina, Baird,’ which should have been 
Daphnia pulex, var. longispina. "The specific name dates back to O. F. 
Miiller in 1785, and is allowed to stand in spite of the vagueness attach- 
1 Ann, Nat. Hist., ser. 7, vol. ii. p. 472. 
2 Nat. Hist. Trans. Northumberland, etc., vol. xiii. pt. ii. pp. 224, 226. 
3 Aun. Sci. Nat., ser. 8, vol. ii. p. 259. 4 Loc. cit. p. 261. 
5 Ann. Nat. Hist., ser. 7, vol. ii. p. 472. 
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