94 SPECIES OF DESMIDS. 



xx. Sides granulate, concave near the ends; semi-cell twice longer 



than wide protractum, 83 



xx. Sides granulate, ends concave; semi-cell twice wider than long, 



biretum var. Floridense* 

 xx. Sides crenate-undulate, converging; cytioderm verrucose, 



Quasillus, 84 

 xx. " rounded, acutely toothed, ends usually nude; cell as long 



as wide Everettense, 85 



xx. " straight, diverging, verrucose; angles rounded, biretum, 86 



yy. Cytioderm granulate; cell widest at base, sides converging, 



sportella, 83 



yy. " " cell narrowed at base, sides straight, diverging, 



protuberanS) 84 

 yy. Cytioderm verrucose; end more or less protruding and scolloped 



(4-crenate) calatum, 86 



yy. Cytioderm verrucose; end more or less protruding, not scolloped, 



ornatum, 82; protractum, 82 



yy. " " end not protruding; semi-cell twice as long 



as wide, oblong-quadrangular, angles rounded, Broomei, 86 



zz. Cytioderm finely granulate or punctate; semi-cells triangular, 



angles rounded, margins smooth Turpinii, 158 



zz. Cytioderm verrucose; semi-cell subreniform, 3 times as wide as 



long conunisurale, 83 



zz. " " semi-cell pyramidal, angles rounded, long, 



tumidum, 75 



zz. semi-cell reniform, angles denticulate, a 

 central inflation granulate ! subcruciforme* 



1 8. TETMEMORUS. FIG. 18. 



Cytioderm smooth or very indistinctly punctate (c). 

 Cytioderm punctate (a). 



a. Cell 3 times as long as wide, irregularly granular; base slightly 

 plicate giganteus, 92 



a. Cell more than 3 times as long as wide (b). 



b: Front and lateral views fusiform; end with colorless, lip-like pro- 

 jection granulatus, 91 



b. Front view cylindrical, not tapering; side view fusiform, tapering; 



end rounded Brebissonii, 91 



* F. w. Algae, p. 27 et seq. 



