FRESHWATER ALG/E 275 



9 Chlamydomonas intermedia Chodat 



In Bull, de VHerb. Boiss. torn, ii, p. 590, t, 22, 23 ; Wille, I.e. p. 142, t, 4, f. 15. 



Forma antarctica. (PI. XXIV, Figs. 19-24) 



Forma minor, stigmata juxta pyrenoidem. 



Long. cell. 12-15 /*; lat. 8-10 ^. 



Hob. Pony Lake. 



Very well-preserved specimens of this species-were abundant among Phormidium 

 autumnale. The cells were ellipsoid, or ovoid- ellipsoid, and somewhat smaller than 

 in the form described by Chodat, but otherwise they were very similar. The proto- 

 plast completely occupied the confines of the delicate cell- wall, and the chloroplast 

 was large and cup- shaped, with a prominent pyrenoid situated in the median line 

 toward the hinder end of the cell. The pigment spot (stigma) was of variable shape, 

 generally elongated and somewhat curved, and was disposed towards one side of the 

 cell, either near the pyrenoid or half way between the pyrenoid and the insertion of 

 the cilia. Two daughter- cells evidently arose by longitudinal division of the mother- 

 cell. (Figs. 23, 24.) 



One cell was observed with two pyrenoids (Fig. 24). This individual was without 

 doubt active when fixed in formalin, but it is possible that the division of the pyrenoid 

 had occurred as an antecedent to cell- division. 



PLEUROCOCCACEjE 

 Genus PLEUROCOCCUS Menegh. 



10 Pleurococcus pachydermus Lagerh. 



In Wittr. et Nordst. Alg. Exsic. No. 447; in Botaniska Notiser, 1882, p. 55. 



Forma cellulis plerumque globosis sed hinc inde anguloso-globosis e mutua pres- 

 sione; crass, membr. cell. 2 p.; diam. cell, matur. 17.5-19.5 fj, cell. juv. (gonid.) 

 8-8.5 M. (PL XXIV, Figs. 45, 46) 



Hob. Green Lake. 



All these cells contained a single parietal chloroplast of considerable extent, 

 furnished with a single pyrenoid. Iodine solution stained this pyrenoid deeply, and 

 also brought out the cell- nucleus. The latter stained well after treatment with 

 osmic acid, and is seen to be situated internal to the chloroplast and rather to one side 

 of the cell. 



Forma stipitata. (PI. XXIV, Figs. 47, 48) 



Cellulis solitariis, libere natantibus, " stipitatis." 



Diam. cell. 18-20 /a; long. stip. 7.5-26 M; lat. stip. 1.8-3.1 M . 



Hub. In pond, Cape Royds. 



The cells of this curious form possessed a cylindrical and more or less elongated 

 appendage at one side. This appendage was generally curved and quite solid, and 



