A HISTORY OF CUMBERLAND 
ing to descriptions of that early period. By Sars it is held to be even 
more variable than D. pulex, so that he was led to make out of it several 
distinct species, which he has since reduced to the rank of varieties. To 
that which Baird figures Dr. Richard gives the designation ‘ Daphnia 
longispina, O. F. M., var. /eydigi, Hellich.” According to the French 
author, ‘one may say without exaggeration that there are as many forms 
of D. Jongispina as there are localities for it.’* The long spine to which 
the specific name refers is the strongly produced hinder extremity of the 
carapace, while in D. pu/ex this caudal spine is very short and in D. 
obtusa rudimentary or wanting. Moreover in the two latter species the 
terminal claws or ungues of the body are provided with secondary den- 
ticles, whereas in D. /ongispina they are simply ciliated. 
To the same family of the Daphniide belongs Mora rectirostris (O. 
F. Miiller), which in comparison with the forms already discussed may 
be set down as one of the very rare species. Dr. Brady in 1898 says, 
“I have myself only once met with it in a pond on Walton Common 
near Brampton, Cumberland, July, 1897.’* ‘The genus is easily distin- 
guished from Daphnia, because the valves, though they have rounded 
corners, are quadrangular instead of oval, and the head by a constriction 
all round has the appearance of being articulated, whereas in Daphnia the 
hind margin of the shell is as a rule continuous. In spite too of the 
specific name rectirostris, the head is not produced downward into a pro- 
minent beak or rostrum as it is in Daphnia. 
From the next family, the Bosminide, Miss Pratt reports the occur- 
rence of Bosmina longirostris (O. F. Miiller), remarking, ‘This species 
appears to be fairly common and widely distributed in Britain. In 
Bassenthwaite it was very common in all the tow-nettings in April, 
but rare in June.’* This minute animal looks as if it had a trunk like 
an elephant. To this appearance the specific name refers, though rather 
inaccurately, because it is not the rostrum itself that is so very long, but 
the first antenne which are attached to its apex, and by their close 
proximity seem in lateral view to be an actual prolongation of it. The 
Bosminidz, like the Daphniidz, have four joints to the dorsal and three 
to the ventral branch of the second antennz, but these appendages, unlike 
those of the Daphniidz, are small instead of large. Here also the feet 
are equally spaced, instead of having the fifth pair as in the preceding 
family separated from the rest by a considerable interval. . 
A third family is represented by the exceedingly common species 
Chydorus sphericus (O. F. Miiller). Miss Pratt speaks of it as Chydorus 
sphericus, Baird, and rightly says that it is ‘common in ponds and ditches 
in Britain almost all the year round,’ including it among those species 
which in Bassenthwaite were abundant in April but rare in June.‘ This 
little spherical species was described by Miiller in 1776 as Lynceus 
sphericus, and the family to which it belongs has often been called 
1 Ann. Sci. Nat., ser. 8, vol. ii. pp. 277, 290. 
2 Nat. Hist. Trans. Northumberland, etc., vol. xiii. pt. ii. p. 245. 
3 Ann, Nat. Hist., ser. 7, vol. ii. p. 471. * Loc. cit. pp. 470, 471. 
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