BY G. I. PLAYFAIR. 133 



1 2 specimens, 1 •(> : 1 •(). Tt lias the iutei'iial, mucous lining com- 

 mon to forms of O. apicidata, but tlie shape is of a different 

 type, and the apex, though pointed, is not apiculate. I have, 

 tlierefore, kept it separate. 



OocYSTis NoRDSTEDTiANA (De Toni) mihi. (PI. ix., f.l3). 



"Celhilse (binje aut quaternte) ellipticje vel fere circulari-ellip- 

 ticae, membrana in utroque fine tuberculo insti'ucta (ut in omnibus 

 speciebus hujus generis plus minus evidenter ])." Nordstedt, I.e. 



Cell. veg. long. 28, lat. 18/^. 



Lismore(185). 



Text-fig.'21.— (a)0. a.ii/mmefrica W. West,(x520); after W. West. 

 (h)0. spec, Schni.,( X 600); after 8chmiclle. (c) 0. rotunda 

 Sehm. ; after 8chmidle. 



Syn., O. Ndgelii forma, Nordstedt, Frw. Alg. N.Z., 1888, p.21; 

 O. Noyelii forma Nordstedtiana De Toni, Sylloge Alg. i., 1889, 

 p.664:; O spec, Schmidle, Alg. aus dem Nyassasee, 1902, p.79, 

 T. iii., f.5. In the first place, it seems to me impossible to place 

 Nordstedt's specimens under O. Ndgelii. The latter is an oblong 

 type verging on the cylindrical, while these are described as 

 ranging from elliptical to almost circular-elliptic. There is also 

 the question of the apical tubercle. From his remarks in paren- 

 thesis, .^upra, Nordstedt seems to have considered its presence as 

 of little importance. Nevertheless (apart from mother-cells; the 

 only published type with an apical papilla is Schmidle's unnamed 

 species from Lake Nyassa. And, in my experience, the apical 

 papilla is exceedingly uncommon; out of 170 specimens of Oocystis 

 measured for these notes, only two showed a papilla; and, of 

 those that showed a slight apiculation, all, without exception, 



