Notes on the Crustacean Fauna of the English Lakes. 419 



In Ennerdale Water, however, this paucity of animal life would 

 appear to be distinctly the result of lack of vegetation : it 

 cannot be dependent on elevation, for the level of the lake is 

 only 369 feet above the sea, and, as has been noticed, the pools 

 close to it swarmed with life. It may be noted also that the 

 members of the family Daphniadte scarcely ever occur, except 

 where there is abundance of vegetation, while the Lynceidse 

 seem to thrive well on a stunted cover of Lobelia Bortmanna 

 or Lsoetes lacustris. 



It may be interesting here to place side by side (as types 

 of the very wide difference existing between the Crustacean 

 faunas of weedy pools of low elevation, and exposed mountain 

 tarns of great elevation) lists of the Entomostraca obtained in 

 two such localities. 



Pools in Ennerlvile : height above the sea, 370 feet. — 

 Baphnia reticulata, D. pulex, D. mucronata, Acantholeberis 

 curvirostris, Ilyocryptas sordidus, Sida crystallina, Bosmina 

 longispina, Lynceus harpce, L. quadrangidaris, L. elongatus, 

 L. truncatus, L. globosus, L. barbatus, Burycercus lamellatus, 

 Biaptomus castor, Gypris loevis, 0. ovum. 



Angle Tarn, under Bowfell: height, 1553 feet. — Bosmina 

 longispina, Lynceus elongatus, L. guttatus, L. exiguus, L. testu- 

 dinarius, L. sphcericus. 



Da.phnia Jardinii, Baird (Figs. 9, 10). — This curious species 

 has, I believe, not been previously figured ; and, indeed, I am 

 not aware that it has been noticed by any observer, except 

 Dr. Baird (Edinburgh, New Philosophical Journal, vol. vi., 

 1857, p. 24). I took three or four specimens in Kydal Water 

 in 1864, and from one of these the drawing given in the 

 accompanying* plate was made. Its claim to specific rank 

 may, however, be reasonably doubted. The produced vertex, 

 by which it is chiefly distinguished from Daphnia pulex, is 

 known in the case of D. mucronata to be a variable character, 

 and the form known as B. comuta is acknowledged to be 

 merely a variety of the latter species. B. Jardinii is indeed 

 smaller and more slenderly formed than is usually the case with 

 B. pidex, but I am not able to discover from my specimens any 

 specific character more valid than that already referred to, nor 

 does Dr. Baird 5 s description indicate any such. On the other 

 hand, it should be stated that the three specimens preserved 

 in my collection all have the cephalic cornua, though of variable 

 size and shape, and I do not remember that any specimens of 

 the normal B. pulex occurred in company with them. The 

 length of my largest specimen is one-sixteenth of an inch, 

 exclusive of the posterior spine. 



Baphnia pidex (Lin.) and B. vetula (Mull.) occur com- 

 monly in lowland pools • and in the peaty hollows in Ennerdale, 



