122 YORKSHIRE NATURALISTs' UNION. 



Van duplex (Kiitz.). [Syn. R. duplex Kiitz. ; R. poly- 

 viorphuin var. signioideuin Rabenh.]. 

 S.W. — ^Cullingworth. 

 Mid W.— Moor-Allerton; Roundhay (W. B. Turner). Baildon. 



Var. spirale West & G. S. West. 

 Mid W. — Hawksworth, in immense quantities amongst vJ/i'W- 

 phyllum spicatuni. Harrogate. 

 N.E. — Pilmoor, near Thirsk. 



582. Rhaphidium setigerum (Schroder) Nob. 



[Syn. Reinschiella ? setigera Schroder]. 



N.E. — Near Rievaulx Abbey. 



The plants we observed agreed well with the description and 

 figures given by Schroder (' Ueber das Plankton der Oder,' 

 Bericht. Deutsch. Botan. Gesellsch., 1897, Bd. xv., Heft 9, p. 

 492, t. XXV., f. 4) except that the setae were a little shorter. 



Length with sette 75 — 88 ju; without set?e 29 — 31 /x; breadth 



57— 6-5 }*■• 



Quite recently Lemmermann has described a plant under the 



name of Closteriopsls longissima which is very closely allied to 



R. setigerum (Cfr. Ploner Forschungsberichten, Teil 7, p. 29, 



t. ii., f. 36-38). He places it in the Desmidieai between Clos- 



terium and Pleurotcenii/m, but in this he is quite wrong, as 



Closteriopsis is not a Desmid. 



In the same paper Lemmermann places R. po/jino/phiiin var. 

 mirabik ^^^est & G. S. West as a distinct species — R. niirabile 

 Lemmerm. In this also he is quite Avrong, as R. polymorphum 

 var. viirabile occurred amongst hundreds of specimens of all 

 forms of R. polymorphum and therefore could only be described 

 as a peculiar form of it. 



Species of Rhaphidium, Scejiedesmus, ai>d Dactylococcus very 

 often (many of them as a rule) possess pyrenoids. 



Raphidium setigerum has not been previously recorded for 

 the British Isles. 



583. Rhaphidium convolutum (Corda) Rabenh. 

 S.^V. — Denholme. 



Trans. Y.N.U.) 1899 (pub. July igoi). Dot. Scries, Vol. 5. 



