D. J. SOOURFIELD ON THE ENTOMOSTRACA OF NORTH WALES. 139 



Entomostracan Fauna op Llyn Padarn and Llyn Peris. 

 Pelagic Fauna. 



CLADOCERA. 



Daphnella brachyura. 

 Daphnia longispina. 



,, hyalina. 

 Bosmina longispina. 

 Polyphemus pediculus. 

 Bythotrephes longimanus. 

 Leptodora hyalina. 



OSTRACODA. 



Nil. 

 COPEPODA. 



Diaptomus gracilis. 

 ,, hircus. 



Cyclops strenuus. 



Littoral Fauna. 



CLADOCERA. 



Eurycercus lamellatus. 

 Acroperus harpoe. 

 Alonopsis elongata. 

 Alona intermedia. 

 Alonella excisa. 

 Pleuroxus trigonellus. 

 Peracantha truncata. 

 Chydorus sphericus. 

 ,, cadatus. 



OSTRACODA. 



Cypria ophthalmica. 



„ serena. 

 Cypridopsis vidua . 

 COPEPODA. 

 Cyclops albidus. 



,, viridis (gigas). 



„ bicolor. 



„ serrulatus. 



„ affinis. 

 Canthocamptus pygmceus. 



Bottom Fauna. 



CLADOCERA. 



Latona setifera. 

 Drepanothrix dentata. 

 Camptocercus macrurus. 

 Alona affinis. 



Chydorus sphericus (also 

 littoral). 



OSTRACODA. 



Cypria serena (also littoral) . 

 COPEPODA. 



Cyclops serrulatus (also lit- 

 toral). 

 Canthocamptus pygma?us (also 

 littoral). 



It will be seen from the above, that these two lakes alone have 

 yielded practically half of the recorded species, viz. 32 out of G7, 

 and no doubt this falls considerably short of the number of species 

 actually living in them. 



