T>. J. SC0T7RFIELD ON THE ENTOMOSTRACA OF NORTH WALES. 133 



CoPErODA.* 



Eurytemora Clausii, Hoek. Seen from one locality only, viz., 

 Brackish pond, Pensarn, Merionethshire (G. S. B.). 



Diaptomus gracilis, G. 0. Sars. This is an extremely com- 

 mon form, and often occurs in enormous numbers. As a rule, 

 according to my observations, specimens inhabiting the more 

 elevated lakes (say 800 feet and upwards) are of a brilliant red 

 colour, while those in the lower lakes are not abnormally coloured. 

 Males with and males without a process on the antepenultimate 

 join 



int of the right first antenna have been seen, but the former 



seem to be more abundant than the latter. 



Diaptomus hire us, G. S. Brady. Presumably a rare species, 

 specimens having been taken only from Llyn Padarn and possibly 

 a few also from Llyn Idwal. Those from the latter lake were 

 immature and could not be quite certainly identified. 



Cyclops fuscus, Jurine. (C. signatus, Koch). Only recorded 

 from the following localities : Llyn yr Afon (G. S. B.), pool above 

 high-water east of Penmaenmawr (G. S. B.), Llyn y Cwn, Llyn 

 Ogwen, and marsh at southern end of Llyn Cynwch, Dolgelley. 



Cyclops albidus, Jurine. (C. tenuicornis, Clans.). Conway 

 Marsh (G. S. B.), Llyn Padarn, Llyn Peris, and Llyn Dwythwch. 



Cyclops oithonoides, G. O. Sars (C. Scour fieldi, var., G. S. 

 Brady). Found only in marsh ditches near Cwm y Glo. 



Cyclops strenuus, Fischer. This species is more capable of 

 being "pelagic " in its habits than almost any other of the genus, 

 and maybe found, as in Llyn Padarn, in company with such forms 

 as Bythotrephes longinianus and Leptodora hyalina. On the other 

 hand, it may often be found in the smallest of pools. Corres- 

 ponding to this diversity of habitat is its remarkable variation, 

 which has led to the formation of several so-called species, e.g., C. 

 victims, C. abijssorum, etc. In the present state of our knowledge, 

 however, these cannot be considered as good species, scarcely even 

 as permanent varieties, and it seems best, therefore, to group all 

 these forms under the one name, C. strenuus, as is done by several 

 recent writers, e.g., Schmeil, Richard, Mrazek, etc. 



* As far as possible the nomenclature used in Schmeil's " Deutschlands 

 freilebende Siisswasser-Copepoden" has been adopted. 



