92 DESMIDS OF THE UNITED STATES. 



by Liindell, but it possesses the principal feature, the "protu- 

 berans" derived from the excess of the diameter of the end 

 of the semi-cell over tlie measure of the base. It differs in 

 the less prominent central inflation, and in having the mem- 

 brane granular, not punctate. Kirchner describes a new 

 species, C. xjaeudoi^rotuberans, which has no central inflation, 

 no granules nor puncta. 



C. Qtr.isiLLrs, Lund. Plate XX, figs. 13, 14, 15. 



Somewhat longer than broad, constriction deep, sinus 

 linear. Semi-cells trapezoid, narrowed from the broad, 

 straight base to the truncate end; sides, below, granulate 

 dentate, above undulate ; end slightly undulate; angles, in- 

 ferior and superior, obtusely rounded ; cytioderm coarsely 

 granulate, the verrucae in subconcentric lines; end view 

 shows a basal, granulated protuberance. 



Diameter 60-70 yu. ; length 66-75 yu. 



I found this form first in the vicinity of Bethlehem, Pa., in 

 the year 1877, and then described it in the " Bulletin Torrey 

 Bot. Club," of Xew York, Vol. VI, p. 186, as a new species, 

 C irregulare, in reference to the irregular size of the crenae 

 of the sides. Later researches revealed Lundell's earlier de- 

 scription. 



Since 1877, have found the same plant in various localities 

 in Pennsylvania, Massachusetts and Xevv Jersey. 



C. EvEEETTEXSE, Wollc. Plate XX, figs. 10, 11, 12. 



Cells as long as wide ; constriction deep ; sinus linear, often 

 much ampliated ; semi-cells with ends broadly rouuded, or 

 truncate, sides convex ; membrane rough with large verrucae 

 arranged in concentric series; apex usually nude, surrounded 

 by short, acute, conical teeth ; end, and transverse view 

 show a decided central inflation. 

 Length and breadth, 50-52 ju. 

 Ponds, ilt. Everett, Mass. 



C. Eloisbanuji, WoUe. Plate XXII, figs. 1, 2. 



Cells large, one-third longer than broad ; constriction 

 forming a deep, linear, outwardly widening sinus on each 

 side; semi-cells semicircular, margins set with long pointed 

 teeth or aculei ; center inflated and grauularly rough, inter- 

 mediate area smooth or punctate ; end view oval with a 

 graniilar tumor on each side, and two somewhat converging 

 series of teeth or aculei extending from end to end. 

 Diameter 75 /<. ; length 100 /^. 



