354 ]\Ir. R. Gmiiey on c<'rliitn 



investigation of the life-historv of this, our only remaining 

 Jiritish Pliyllopod, are required. 



Cladocera. 



The two species mentioned below were botii found during 

 August and September 1919 on East Ruston Common, 

 three miles north-west of Stalham, in East Norfolk. At 

 the spot where I have made my eollections the marsh is 

 erossed by a road at its narrowest part, and on the south 

 of the road is a bog which is always under wat( r. There 

 is a rich vegetation of the usual feu type, with a dense 

 growth of Hy[)num below the water, with whieh is mingled 

 Utricularia viiuor and intermedia. The jiresence of Chara 

 in a pool iu the marsh indicates a calcareous water. The 

 ]"]ntomostracan fauna is of remarkable richness, and differs 

 in several res])ects from that of any waters with which I am 

 acquainted. Twenty-four species of Cladocera and twenty 

 of Copepotla have been found in a small space of a few square 

 jards, besides .'several Ostraeoda ; while some of the species 

 are extremely rare in other parts of the district, but occur 

 liere in considerahle numbers — for example, Metnct/pris cor- 

 dtita, ('i/pris fusciuta, Candona eajjlcctcllu, Cyc/ojjs nanus, 

 and Canthocamptus northumhriciis. The two species, Cerio- 

 dnphnia setusa and Kurzia lalissima, were found only in this 

 one small sj)ot and not elsewhere in the marsh. 



2. Ccriadaphma setosa, Matile. (Fig. 1.) 



A few specimens of this peculiar Ceriodophnia were found 

 in a collection made on Aug. 26 in moss under a depth of 

 about six inches of water. I returned to the spot two days 

 later with the intention of obtaining more material, but was 

 again rewarded only by a very few individuals iu sjjite of 

 exhaustive search, and was not able to ascertain in what 

 kind of situation it was living. Its almost entire absence 

 from eolleetioDs made in the clear open water seems to show 

 that it lives actually among the moss, whereas ('. laticuudata, 

 which was also present at the same time, was commoner in 

 the open water. C. setosa is a sluggish swimmer, and is 

 easily distinguishable from the usual red form of C. lati- 

 caudata by its whiiish colour faintly tinged with rose ; but 

 this cliaracter is not altogether distinctive, since I liave 

 found C. laticaudata in abundance in a similar situation at 

 Sutton Broad, every individual being of exactly the same 

 colour as C. setosa. In fact, 1 sup|)Oscd at the time that I 

 had found a new habitat for the latter. 



