BRITISH FRESH-WATER ENTOMOSTRACA. 435 



these we certainly have in this country, viz., D. hyalina s. str., 

 D. lacustris Sars, and D. galeata Sars. The fourth, D. pellucida 

 P. E. Miiller, probably occurs also, but is certainly not common. 



If all these forms can be grouped together as one species, I do 

 not see quite clearly how they can be kept apart from D. longi- 

 sphia, which does not seem to differ so much from some of them 

 as they do from one another. 



With regard to the distribution of the variety galeata it may 

 be mentioned that the form occurring in Epping Forest and the 

 south-east of England generally is not the typical galeata such 

 as occurs in the north of England, Scotland, and Ireland, but 

 the smaller form referred to by Lilljeborg as approaching 

 D. cucullata. 



D. cucullata Sars. 



"^ D. jardinii Baird (2).* 



D. hairdii Forrest (8). 



Hyalodaphnia jardinii and H. kahlhergensis Brady (5). 



D. jardinii Hodgson (10). 



Scapholeberis Schoedler. 



S. mucronata (0. F. Miiller). 



Daphnia mucronata Baird (1), Brady (4). 

 Both the cornuta and the typical forms occur, often associated 

 together, but the latter does not appear so early in the year as 

 the former. 



Simocephalus t Schoedler. 



S. vetulus (0. F. Muller). 



Daphnia vetula Baird (1) Brady (4). 

 One of the commonest of the British Cladocera. 



S. exspinosus (Koch) (? De Geer). 



Daphnia vetula Baird (in part) (1). 

 A fairly common species in the south and east of England, but 

 not yet recorded from the north or from Scotland. 



* See note on previous page. 



t In a paper in the "Annals and Mag. Nat. Hist. " for April 1903, Canon 

 Norman proposes the name Simosa for this genus, as Simocephalus was 

 previously used for a genus of snakes. 



