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



I do not think my records, and observations justify any further 

 remarks directly dealing with the Entomostraca of North Wales, 

 but before concluding- I would like to say a few words on two 

 points having an important, if indirect, bearing upon the subject 

 in hand, viz., the general character of the lakes, and the methods 

 of collecting. 



As regards the first point, the most noticeable feature is that the 

 lakes of North Wales are remarkably uniform in type, and in 

 complete contrast to all those of this South-eastern part of Eng- 

 land. They are almost without exception collections of the clearest 

 and purest water, lodged in rocky basins of considerable depth, and 

 surrounded by stony margins, which may, however, be more or less 

 obscured by peat and bog-moss. They are, moreover, practically 

 free from macro-vegetation. Micro-plants, especially free swimming 

 alga?, are probably not less common in the lakes of North Wales 

 than they are here, but the luxuriant masses of Myriophyllum, 

 Elodea, Starwort, Duckweed, etc., found in the majority of our lakes 

 and ponds are quite without parallel there so far as my experience 

 goes. Many of the lakes are absolutely destitute of any visible 

 vegetation, except perhaps some bog-mosses or a rather weak 

 growth of filamentous alga on the stones near the margin, and 

 where higher forms of plant life do occur they are generally limited 

 to horse-tails (/iquisetuni), Lobelia (X. Dortmanna), or more 

 rarely buck-bean (Menyanthes trifoliatd) . Probably in the depths 

 of many lakes members of the Characea? flourish, but the only 

 direct evidence I have of this is that I obtained a species of 

 Nitella pretty plentifully from several parts of the bottom of Llyn 

 Padarn. 



Such being the general features of the lakes and their vegeta- 

 tion, it could not be expected that the littoral fauna, which in all 

 branches of pond-life includes the bulk of the species, should be a 

 very rich one, and this accounts, no doubt, for the absence of many 

 of what are to us the commonest species. On the other hand, the 

 lakes seem eminently suited to the pelagic forms, and these, as 

 regards the Entomostraca, have already been shown to be well re- 

 presented,* for although the number of species recorded (10 or 11) 



* This is probably true also of the Rotifera. I have repeatedly found 

 C on ochilus unicornis in the lakes of North Wales, and Asplanchna prio- 

 donta, Notholca longispina, Anurcea aculeata, etc., have also been seen. 



