SPECIES OF DESMIDS. 103 



1 Diameter 6o-ii2/* (^ to -fa in.) (b). 



^[ " 32/f (y-J-o in.); granulate-crenate luteolum* 



1 " 13-16/1 (T^O to TsVo in -)> 



muttcum, minor, 119; Bieneanum, 124 



. Sides slightly constricted near the angles, especially in end-view, 



tumidum, 120 

 1). Sides not constructed; diameter ^ to yjy in. (75-S3//), 



grande, 120 



<. " " " diameter jj^ in. (6oyu) . . . inerme 122 



^r. Angles mucronate (d}. 



c. Angles aculeate, spinous, awned or notched (<?). 



d. Mucros double on basal angles, none on the end in front view; 



semi-cells truncated triangles paniculosum, 124 



d. Mucros single on all angles, horizontal; diameter less than -^-^ in. 

 (5oyu); semi-cells not quadrangular . . . brevispina, 121 

 d. Mucros single on all angles, horizontal; semi-cells quadrangular, 



quadrangular e, 145 

 d. Mucros single on all angles, diameter larger than -fa (SOJM), 



magnum, 120 



d. Mucros single, oblique downward and inward; diameter ^-J-^ 

 (ioo//) or more majusculum, 121 



d. Mucros single, oblique downward and outward; diameter -^-^ 



(45 //) or less Dickiei, 122 



e. Aculei or awns i on each angle (/). 

 e. 2 on each angle (g). 

 e. " 3 on each angle (w). 



e. 4 or more on each angle (ww). 



/. Semi-cells elliptical, often angular, approximate; ends straight, 

 concave or convex; awns horizontal, diverging, converging or 



upwardly oblique; diameter ^ to T oVo in - ( 2 5~3 8 X)> 



dejectum, 121 



/. diameter -fa to -fa, (55-60^), cornutum* 



f. Semi-cells elliptical, separated by a long, narrow isthmus, 



cuspida turn, 123 

 /. " triangular-fusiform; awns long; diameter -fa to -^ 



(50 57/^) megacanthum, 121 



f. Semi-cells triangular; sinus with a small spine on each side, 



Leivisii, 122 



f. " " sinus without a spine . . aristifcrum, 122 



/. Semi-cell quadrangular, margins toothed or spinous, 



quadr angular e, 145 

 *F. w. Algae, p. 41. 



