134 OOCYSTIK AKD ER EMOSPHiERA, 



appei'tainecl to O. apiculata West, of which species the apicuhxs 

 is characteristic. Nor is the papilla more cominoii in Ercmo- 

 sphosra viridis {which, from my j^oint of view, is an Oocystis). Out 

 of 70 specimens measured, it occurred in no more than two. The 

 only forms in which the tubercle seems to be indifferently present 

 or absent are O. panduriformis West, and Erem. viridis v. 

 doliformis mihi. 1 have never noted either tubercle or apiculus 

 in any form which is generally non-tuberculate or non-apiculate. 



Var. ROTUNDA (Schm.) mihi. (Text-fig. 2 Ic). 



Cell, rotundfe, 10-lI/x latse, utroque polo tuberculatpe." 

 Schmidle, I.e. 



Schmidle, Beitr. z. Alpinen Algenfi., p.8, T.14, f.7a, ^ 1895. 

 I have not noted the occurrence here of this form, which seems 

 to me to be a more globose variation of O. Nordstedtiana. Nord- 

 stedt's smallest size is 16 x 10/>i. 



Oocystis Chodati, nom.nov. (PI. viii., f.8-11). 



Cellulse ovales vel ovali-oblonga?, ubique sequaliter rotundatse; 

 lateribus arcuatis, apicibus late-rotundatis nee apiculatis, nee 

 incrassatis. Chloroplastides pulviniformes. 



Cell, matric. sphfer. diam. 3.3-40, oval. long. 30-47, lat. 25-40; 

 cell. veg. vel autosp. 16x 12, 18x 12, 20x 12, 24 x 10, 24 xl8, 

 28 X 22, 30 X 20, 34 x 25, 40 x 30/x. 



Auburn (49, 56, 135); Guildfoi-d (60, 124, 146); Fairfield(l 12). 



Syn., 0. solitaria, pro parte, in Chodat, Alg. vertes, p. 189, 

 f.l04F, autospores. This species is regularly oval or oval-oblong, 

 rounded everywhere. It differs from 0. solitaria especiall}- in 

 the broadly rounded ends without papilla or internal incrassation. 

 Also, the cells being broader, the axial ratio is smaller. The 

 latter varies, in the examples given above, from 1'3 to 1'6:1"0, 

 the average being 1 "4 : 1 '0. In 0. solitaria, the ratio is greater, 

 the cells being proportionately longer and more pointed. Some 

 of the smaller sizes of 0. Chodati come very near to 0. Ndyelii; 

 the cells, however, are broader in proportion and more oval. 

 This form is generally found on swampy ground, especially the 

 larger sizes. 



