102 SPECIES OF DESMIDS. 



23. STAURASTRUM. FIG. 23. FOUR FORMS. 



T With numerous processes, their ends more or less divided ( ) 



T Without processes, the angles in front view produced or not () 



Cytioderm smooth or finely punctate (i). 



Cytioderm verrucose or granulate (2). 



Cytioderm hirsute, spinulose or thorny (3). 



End view 2-armed, body broadly ovate; arms serrate, apices 



finely toothed Minneapoliensc* 



End view 3 or 4 angled (B). 



End view 5 or 6-angled, apices of (6) rays rounded and spinulose, 



Kissimmense* 



" 5 angled, apices spinous (G). 



End view 6-angled, apices of cylindrical processes slightly 



notched, 4 processes within the margin; end view hexagonal, 



Wollcanum* 

 apices of (5-6) rays trifid, distended, 



distentum, 149 

 End view 8-angled; rays a whorl of 8 below, 4 above, 



tetroctoceru M, 151 



End view circular, rays a whorl of 9 below, 6 above, artiscon, 148 

 " u rays marginal, very short, usually 9, ends notched, 



Eloiseanum, 1 49 

 i. Angles of semi-cell in front view not produced; rounded and 



smooth (a). 

 i. " " " " " mucronate, spi- 



ous or notched (c). 



1. Angles of semi-cell in front view produced more or less (/i). 



2. Angles of semi-cell in front view more or less produced (/"). 



2. " ' " " " not produced (gg). 



3, Angles of semi-cell in front view more or less produced (oo). 



3. " " " " " not produced (yy). 



a. Semi-cell oval or elliptical, ends not inflated ( f ). 



a. " " " ends inflated; diam. j-gVir m - ( 2 5/^)' 



bacillare* 



a. Semi cell semi-circular, smooth, sinus narrow, linear, orbiculare, 120 

 a. Semi-cell almost circular, sides finely dentate . . Cosmarioides* 



a. " sides smooth vesiadatum* 



a. Semi-cell triangular, sides concave trihedrale, 123 



a. Semi-cell cuneate; cell slightly longer than wide, 



pseudopachyrhynchum, 125 

 *F.-w Algae, p. 41 et seq. 



