90 SPECIES OF DESMIDS. 



j. Ends rounded; semi-cells subsemicircular, with 8-10 crenulations, 



Sendtnerianum* 



s. Ends truncate; semi-cells pyramidal; cells small, . . notabile, 66 

 s. " sides almost parallel; diameter ir j ir to -g^ in. 



(30-38^), crenatum, 67 



s. " sides converging; diameter y^- in. (20 jj), 



Ncegelianum, 67 



/. Semi-cell quadrate, smooth, angles rounded; end retuse or convex, 



quadratum, 59 



/. pyramidal or subquadrate; end undulate, Holmiense, 68 



/. " " end truncate; diameter ^ to ^in. (32-36/4), 



integritm, 68 



/. diameter y^ to y^Vo in - ( 2 - 2 4/^), 



Hammer i, 79 



/. " " end rounded, surface smooth, octogonum* 



t. Semi-cell pyramidal, punctate, base flat, angles rounded, 



ansatum, 68; Nymannianum, 79 

 /. Semi-cell sub-semicircular, end truncate, sides with 2 emargina- 



tions; smooth Braunii* 



. Ends truncate. Diameter -^ to Yg^jr i n - ( 20 -3/0> puncn-latum, 74 

 ^. Ends convex. Diameter Ig 1 00 to YFOT ^ n ( I 4~ 1 ^^ 1 ) ^ ; <?, 62 

 f. Cell twice as long as wide, rectangular; sinus linear, not widened, 



sinuosum, 65 

 f. Cell less than twice as long as wide; semi-cell pyramidal, 



venustuni) 68 



v. " " " " semi-cell subquadrate, small, 



Me?ieghinii) 65 



/. Sinus narrow, not widened outwardly; cell elliptical, end convex, 



variolatum 63; exigttum, 66 

 w. Sinus widened and rounded inwardly, narrowing outwardly, cell 



wider than long obsoletum, 64 



ix). Sinus widened outwardly; semi-cell oval, base and end convex, 



contractum, 63 

 w. " " " " base and end flattend, 



depressum, 64 



w. Sinus widened outwardly; semi-cell quadrate, Meneghinii) 65 



w. " semi-cell subsemicircular, end rounded; 



diameter -g-J-g- to -^^ in. (75-100^) .... pachydermum, 70 

 jc. Margins crenate or granulate (y). 

 x. Margins not crenate nor granulate (bb). 



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



