14 F. E. FRITSCH. 



Forma minor (PL I., fig. 27). 



( 'ellulis multo minoribus, 7-8 p latis, cxacte globosis vel modicc anguloso-globosis 

 e mutua prcssione, in familiis parvis cell alarum sequalium aggregatis intra stratum 

 Phormidii nidulantibus ; membrana cellulae codem niodo quo iu typo incrassata ; 

 chromatophora cum pyrenoide. 



This form gives rise to one-layered strata of circular or somewhat polygonal cells 

 of almost uniform size. This going hand in hand with the small dimensions of the 

 cells gives the strata a very characteristic regular appearance, in marked contrast to 

 the generally non-uniform strata of the larger-celled type. The cell-membrane is 

 prominently thickened to the same relative extent as in the larger forms, and the 

 cells have a conspicuous pyrenoid. 



Forma robusta W. and G. S. West, op. tit., p. 276, PL XXIV., figs. 52-54. 



(PL I., figs. 34-35). 



Cellulis majoribus vel multo majorib us, 35-78-100 /A latis, globosis vel distincte 

 ellipsoideis, intra stratum Myxophycearum uidulantibus, solitariis vel saepe dense 

 aggregatis ; membr. cell. 2 5-6 /x crassa et lamellosa ; chromatophora saepe distiucte 

 parietal!, globulis oleariis nullis vel magnis et conspicuis. 



The cells of this form attain immense dimensions and, although ordinarily 

 spherical, as the Wests' figures show them, are sometimes ellipsoidal (figs. 34, 35). In 

 my material the cells of this form generally contained large and conspicuous 

 oil-globules between the membrane and the contents. A pyrenoid does not appear- 

 to occur. Occasionally the cell-contents are reddish-brown (cf. above). The outer 

 surface of the wall is frequently somewhat irregular, giving the appearance of flakes 

 of membrane becoming detached. 



Fonnajilamentosa (PL I., fig. 28). 



Cellulis globosis vel modice depresso-globosis, 14-20 /x latis, in filamentis brevibus 

 dispositis, intra stratum Myxophycearum nidulantibus, cum pyrenoidibus conspicuis. 

 This form is rare. 



Forma simplex (PL I., figs. 30, 31, 33). 



Cellulis globosis, 18-35 JJL latis, solitariis vel in familiis aggregatis, intra stratum 

 Myxophycearum nidulantibus vel libere natantibus, sine pyrenoidibus, sed cum grauulis 

 amylaceis rnultis. 



This is the form originally described by Messrs. W. and G. S. West. The form 

 with small pyrenoids shown in fig. 32 connects f. si>nj>l<',r with f. 



Forma stellata (PL I., fig. 29). 



Cellulis globosis, ut in forma typica, saepe ca. 30 M latis, cum globulis oleariis 

 couspicuis, radiatim circum cytoplasma cellularum dispositis. 



