92 SPECIES OF DESMIDS. 



ee. Cells twice or more longer than wide (ff). 

 ee. Cells less than twice longer than wide (gg). 



f. Cells cylindrical, sides parallel (sometimes rounded); verrucse ob- 

 tuse amcenum, 78 



ff. " " " verrucas emarginate, in lines, 



cUgantissimum, 78 



gg. Semi-cells oval or elliptical . . . tumidum, 61; orthosticum, 78 

 gg. " semi-orbicular, tetraophthalmum, 75; intermedium, 75 



////. Semi-cells pyramidal, end truncate; basal angles rounded, 



octhodes, 76; Botrytis, 74 



hh. Semi-cells oval or elliptical, approximate .... trigonum*' 



margaritiferum, 75; punctula turn, 74 



hh. " " " remote, granulate, portianum, 77 



hh. Semi-cells quadrangular, ends truncate; diam. ^-5-- -5^(60-73/4), 



conspersum, 75 

 /z^. " " ends concave retusum* 



hh > " " diam - AT- -rk (30-45 /^), 



pseudobroomci, 86 



^. " " diam. -^^-^-^ (13-14^), 



sphalcrostickum* 



hh. Semi-cells subreniform, sinus widened and rounded inwardly, 



latum, 76; renifonne, 76; pardalis* 



hh. Semi-cells subspherical, approximate .... orbiculatum, 77 

 hh. Semi-cells hemispherical, remote; base flattened, excavatum, 77 

 it. Ends and sides with teeth; sinus narrow, widened outwardly; basal 



angles rounded Brebissonii, 75 



it. Ends without teeth, sides with 10 to 20; sinus gaping, dentatum, 76 

 jj. Margins crenate; semi-cell semicircular, nuclei 2, end truncate, 



cruciatum, 81 



jj " undulate; sinus widening outwardly, homalodcrmum, 81 

 jj. " " sinus not widening outwardly (kk). 



kk. Cell longer than wide; diameter yj-g- to -g-J-g- in. (38-44^), 



sublobatum, 80 

 ^. Cells longer than wide, diameter ^-^ to ^-^ in. (22-25^), 



margaritum, 80 



. Cell not longer than wide, end truncate .... retusum, 80 

 //. Diameter ^gi^-g- in. ( 1 2//), end truncate; sides convex, often ob- 

 tusely angled centrally Schliephanckeamim, 82 



//. Diameter greater than (i2/*) -%fa* m - ( mm )- 

 *F.-w. Algae, p. 25. 



