Prof. E. Ray Lankester on new British Cladocera. 53 



VIII. — Oil neio British Cladocera discovered hy Mr. Conrad 

 Beck in Grasmere Lake^ Westmoreland. By E. Ray 

 Lankester, M.A., F.R.S., Jodrell Professor of Zoology in 

 University College^ London. 



Two years ago I identified Leptodora hyalina, Lillj., and 

 Hyalodaj)hnia Kahlhergensis^ Scliodl., as British Cladocera in 

 specimens sent to me by Mr. Bolton, of Birmingham, who 

 had obtained them from the Olton reservoir near that town. 



But few of the remarkable forms of Cladocera which occur 

 in tlie larger lakes of Continental Europe had previously been 

 recognized as occurring in this country j and it was therefore 

 interesting to establish the occurrence of the two species above 

 named. 



The list of British Cladocera has now been extended 

 by the observations of Mr. Conrad Beck, who, during the 

 past summer, examined the Entomostracous fauna of Gras- 

 mere Lake, and made careful drawings of the specimens 

 obtained, which he was kind enough to submit to my exami- 

 nation at University College. Mr. Beck has been able to 

 refer the forms observed by him to the following species, 

 three of which are new to British waters ; and I may add that 

 I have compared his drawings with the published drawings 

 of these species and can confirm the accuracy of his identi- 

 fications. 



1. Leptodo7'a hyali/ta, Li'iW^eh. ^. Taken Sept. 16th. 



2. HyalodaphniaKahlhergensis, Schodl. Abundant, 8ept. 9th 



to 16th. 



3. Holopedium giljberiim^ Zaddach. Thirty specimens, each 



encased in a gelatinous globe, Sept. 7th to 16th. 



4. Latona setifera ^ and ? , Straus (Weissman) . Sept. 3rd 



to 14th. 



5. Bythotrephes, sp. Sept. 14th. This appears to be a new 



species, distinct from the Bythotrephes longimanus of 

 Leydig. 



At the same time, together Avith these interesting species, 

 hitherto unknown in Britain, Mr. Beck observed and made 

 drawings of the following, already known to Baird as British 

 species, some being of i-are occurrence : — Sida crystallina^ O. 

 F. Miiller (Sti-aus genus) ; Daphnia vetida, Miiller, and D. 

 reticulata, Jurine ; Eurycercus lamellatusj O. F. Miiller (Baird 

 genus) ; Alona quadrangidaris, Miiller (Baird genus) j Pera- 

 cantha truncata, Miiller (Baird genus). 



It appears probable that in lakes where species of the Sal- 

 monid Coregonus are found, there also v/ill be found the large 

 deep-water Cladocera, such as Holopedium and Bythotrephes, 

 which serve these fish as food. 



