SPECIES OF UESMIDS. 89 



//;. Cell nearly as long as broad; semi-cells rhomboid, sides all 

 equal; sinus deep, wide .... . rhombusoides.** 



n. Ends rounded; semi-cell subcircular, sinus a mere notch, 



globostim, 60 

 n. " " semi-cell subsemicircular (<?). 



//. " " semi-cell oval (;-). 



n. " " semi-cell elliptical, or hexagonal-elliptical; cell -^ 



longer than wide; diam. 25-42/Y, sexangulare, 63 



n. Ends rounded semi-cell elliptical; cell ^ longer than wide; diam. 



25-26;^ . . . 7incrosphtnctuj?i.** 



n. Ends truncate; semi-cell hexagonal; diameter xsVt i"- (^i/") or 

 less, . ....... polygonum, 65 



n. Ends truncate; semi-cell triangalar; diameter -j-J^ in. (50/i) or less. 



galei-ituin, 70 

 n. " semi-cell subsemicircular, smooth; sinus deep, nar- 



row . nitidulum, ()2\ psendonitidulum, 62 



11. " " " punctate or granular; si- 



nus narrow . ... lobulatuliim .'^ 



0. Sinus deep, narrow (/). 



0. Sinus deep, wide, almost linear; cytioderm smooth, sejunctum, 62 



o. " rounded or oval; semi-cells lunately curved; cytioderm 



punctate ... . lunatum, 65 



o. Sinus deep, wide, obtuse; semi-cells widening from a narrow base, 



inflatum.^' 

 &. Sinus acute angled, enlarging outwardly, rarely linear, 



perforatum* 

 p. Cell elliptical; basal angles acute . .... Baileyi, 64 



/. Cell suborbicular; basal angles obtuse; diameter -^^ to -^-^ in. 



(60-1 oo/<), Ralfsii, 69 



/■ " " " diameter -^^ to ^ in. 



(30-38), . .... . . constricium, 58 



r. Cytioderm centrally somewhat granular; nucleus i in each semi- 

 cell, .... ... . tumidu}n, 61 



r. " smooth or punctate; cells small, 



bioculatum, 60; tinchim, 61 

 s. Ends rounded; semi-cells semi-orbicular; crenae usually 9, 



undulatum, 67 



s. " " semi-cells subsemicircular; margins finely crenulate- 



dentate . . . Wolleannm* 



* Journ. R. Micr. Soc, Dec, 1885. f Journ. R. Micr. Soc, Feb., 1886, 

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



