D. J. SCOURFIELD ON THE ENTOMOSTRACA OF NORTH WALES. 129 



England,* for it occurs plentifully, and apparently to the complete 

 exclusion of B. longirostris, which is the typical representative 

 of the genus in the latter district. 



Acantholeberis cuxvixostxis, 0. F. Miiller. I have only seen 

 this in a collection from Arthog Marsh (G. S. B.). 



Drepanothrix dentata, Euren. Two localities have yielded this 

 peculiar species, viz., a tarn near the summit of Allt Wen (G. S. 

 B.) and Llyn Padarn. 



Euxycexcus lamellatus, 0. P. Miiller. A fairly common 

 species, but not usually found in the larger lakes. 



Acxopexus haxpae, Baird. Not very common, the role it plays 

 in the south-eastern part of England being partly undertaken 

 perhaps by Alonopsis elongata. 



Camptocexcus macxurus, 0. F. Miiller. The few examples 

 seen were from Llyn Padarn. They were of the type called 

 " rectirostris " by Schoedler, which is probably the common 

 British form, for the drawings given by Baird and also by Norman 

 and Brady seem to indicate this variety, and, so far as I can 

 remember, it is the only one I have ever taken. 



Alonopsis elongata, G. 0. Sars. (Lynceus elongatus, Norman 

 and Brady, " Mon. Brit. Ent.") This is one of the most abundant 

 and most widely distributed of the Cladocera of North Wales, but 

 it was not found either in Llyn Padarn or in Bala Lake. Most 

 of the specimens seen were of a very dark colour, some, indeed 

 being almost black. 



Leydigia acanthocexcoides, Fischer. Only one locality has 

 yielded this species, viz., a tarn near the summit of Allt Wen (G. 

 S. B.). The specific mine acanthocercoides has been retained 

 because it is believed that Fischer's species is the same as Leydig's 

 Alona quadrangularis. If there is a genuine difference between 

 the two, as asserted by some authors, then there is no doubt that 

 the present, which is the common British form, should be called 

 L. quadrangularis, Leydig. 



Alona quadxangulaxis, 0. F. Miiller. Examples of this 

 species have only been obtained from a " pool above high-water 

 mark" east of Penmaenmawr (G. S. B.). 



Alona affinis, Leydig. This species, which is probably the 

 same as P. E. Miiller's A. oblonga, has been noted in company 



* By this phrase is intended the whole district lying to the east of a line 

 drawn from The Wash to the Isle of Wight. 



