128 THE AMERICAN MONTHLY [July, 



z. Verrucse none central, marginal i or 2 rows ; cell about twice longer 



than wide ovale^ 57 



z. Verrucae none central, marginal i or 3 rows ; cell less than twice longer 



than wide tripJicatum. 73 



z. VerruciE centrally scattered, marginal in series of 3 each ; semi-cell quad 



rate, angles rounded triplicatiun^ 73 



aa. Central verrucse 3, in a single row Do7i)ieIUL 71 



aa. '• 6, in a triangle, apex toward the isthmus, 



polymaziim., 70 

 aa. " 6 or 9, in 3 or 3 transverse rows ; marginal rows 1 or 



2 ; semi-cell semicircular . . . Kitchellii^ 72 ; suborbictilare. 7S 

 aa. Central verrucae 10; semi-cell semicircular, end truncate, 



anisochondriim. 73 

 aa. "• circularly clustered ; semi-cell twice longer than wide 



sides emarginate, fend truncate Seelyanum^ 73 



bb. Centre granularly rough and punctate ; margin smooth ; semi-cells oval 



tt(midiim^ 61 

 bb. Centre with 3 verrucae in a row ; semi-cells semicircular, Do?i?iellii\ 71 

 bb. Central verructe i at the isthmus, S or 9 marginal in i or 2 curves, 



taxichondrti7n. 71 

 bb. " 4 near the isthmus ; semi-cells semicircular ; end some 



what truncate; basal angles often pointed, pscudotaxicho7idrum. 71 

 cc. Chlorophyll dirtlised {dd). 



cc. '• concentrated into i or 3 nuclei {ee) . 



dd. Marginal verrucie or granules rounded {///i). 

 dd. " •• conical or pointed (//). 



ee. Cells twice or more longer than wide (Xf)- 

 ee. Cells less than twice longer than wide {g'g) . 



ff. Cells cvlindrical. sides parallel (sometimes rounded) : verruCcC obtuse, 



a?n(Xfi7tm^ 78- 

 jy. " " " verrucie emarginate, in lines, 



elegantissimum. 78 

 gg. .Semi-cells oval or elliptical . . . fuf/iidum. 61 ; ort/wst/'citm, 78 

 gg. " semi-orbicular . tctraopJithab)7um. 7s : intermcdhim. 75 



h/i. Semi-cells pvramidal. end truncate ; basal angles rounded, 



octJiodes. 76 ; Botrytis. 74 

 hh. •' oval or elliptical, approximate, 



jnargaritiferiitn^ 74 J puiictulatitm., 74 

 hJi. '' " '• remote, granulate . . portianum., 77 



Jih. Semi-cells quadrangular . . . conspei-sum^ 75 ! pscudobroomei., %G 

 hh. '* subreniform. sinus widened and rounded inwardly, 



latum. 76 ; renifornie., *]6 



hh. " subspherical. approximate orbicuIaticfH. 77 



hh. " hemispherical, remote; base flattened . . excavatia?i^ 77 



//. Ends and sides with teeth ; sinus narrow, widened outwardly ; basa 



angles rounded Brebissoiiii. y^ 



ii. Ends without teeth, sides with 10 to 30 ; sinus gaping, dentatum^ ']6 

 jj. Margins crenate ; semi-cell semicircular, nuclei 3, end truncate, 



crjiciatmn., 8i 

 jj. '' undulate; sinus widening outwardlv . homalodermu?n.,'^\ 



jj. " "• sinus not widening outwardly {kk^. 



kk. Cell longer than wide ; diameter 5^ to -^\-^^ in. (38-44,^), 



siiblobatum. 80 



