SPECIES OF DESMIDS. IO3 



Tf Diameter 60-1 12/< (^|^ to ^|^ in.) (6). 



T" " 32/< (y|-g- in.); granulate-crenate . . . I'lteohmi* 



1 " 13-16/t (yfo to T3V0 in-); 



mulicum^ minor, 119; Bieneammi, 124 



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



tumidum, 120 

 6. Sides not constructed; diameter -5-1-^ to -^ in. (75-83//), 



grande, 120 

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



^. Angles mucronate (d). 



c. Angles aculeate, spinous, awned or notched (e). 



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. 

 (50/i); semi-cells not quadrangular . . . brevispina, 121 

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



quadra?zgttla7-e, 145 

 d. Mucros single on all angles, diameter larger than 3^^ (So/<), 



magnum, 120 



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



(looyu) or more tnajuscuhmi, 121 



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



(45 yu) or less Dickiei, 122 



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

 e. " 2 on each angle i^g). 

 e. " 3 on each angle [vv). 



e. " 4 or more on each angle {ww). 



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



concave or convex; awns horizontal, diverging, converging or 

 upwardly oblique; diameter -^^ to y^jVo- in. (25-38/1), 



dejectum, 121 

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



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



cuspidatutn, 123 

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



(50-5 7/t) .... megacantimm, 121 



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



Lewisii, 122 

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



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



quadr angular e, 145 

 *F.-w. AlgEE, p. 41. 



