234 OTf THE BRITISH SPECIES OF ENTOMOSTEACA 



Daphnia hyalinaj var. pellucida, P. E. MiiUer, (PL X., 



figs. 14, 15). 



1867. Daplmia pellucida, P. E. Miiller, Danmarks Cladocera, 



p. 116, pi. I., fig. 5. 



1890. ,, hyalina, var. pellucida, Gr. O. Sars, Oversigt 



af JTorges Crustaceer, pp. 10, 34. 



1892. ,, ,, Scourfield, Some new Eecords of British 



Cladocera (Journal of Quekett Microscopical Club, vol. 



v., Ser. 2), p. 66, pi. Y., fig. 1. 



Female. — Outline as seen from the side subovate, with a very 

 long, slender, and slightly curved spine. Head occupying about 

 one-third of the length of the body, well rounded in front, ventral 

 margin straight or very slightly sinuated and terminating in a 

 slightly produced beak : dorsal border of the shell forming a 

 continuous very gentle curve, somewhat flattened in the middle, 

 ventral margin rather boldly convex. The post-abdominal spines 

 are slender and simple except for a fringe of excessively delicate 

 hairs ; in front of the unguis is a marginal series of 10-12 curved 

 setae, progressively increasing in size from behind backwards : 

 dorsal abdominal processes obsolete. Eye rather large, placed 

 near the centre of the head ; between it and the rostrum is 

 generally visible a minute eye-spot. Shell often very distinctly 

 chequered : in other oases nothing but a granulated structure is 

 visible. Length, 1'8 mm. ; height, '9 mm. 



Hah. — Duddingston Loch, near Edinburgh. Eor specimens 

 from this locality I am indebted to the Eev. Canon Norman, 

 r.E,.S. I do not certainly know of its occurrence elsewhere 

 in Britain, but the Duddingston specimens agree exactly with 

 Swedish ones named by Professor Lilljeborg and sent by him to 

 Dr. Norman. 



This form was described by Dr. P. E. Muller as a distinct 

 species under the name Baphnia pellucida. Dr. Muller has, 

 however, more recently {fide Gr. 0. Sars) withdrawn the specific 

 name, considering it to be merely a variety of Z). hyalina, Ley- 

 dig. Mr. Scourfield has recorded the typical D. hyalina horn. 

 several localities in Essex, and has kindly sent me specimens : 

 they certainly approach very closely the variety here desciibed. 



