92 DESMIDS OF THE UNITED STATK-. 



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

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

 of the semi-cell over the 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. pscudoprotuberans, which has no central inflation, 

 no granules nor puncta. 



C. QUASILLUS, 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; eytioderm coarsely 

 granulate, the verrucae in subconcentric lines; end view 

 shows a basal, granulated protuberance. 



Diameter 60-70 yt/. ; length 66-75 ^ 



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. irregularc, 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 Xew Jersey. 



C. EVERETTENSE, Wolle. Plate XX, figs. 10, 11, 12. 



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

 much ampliated ; semi-cells with ends broadly rounded, 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 >u. 

 Ponds, Mt. Everett, Mass. 



C. ELOISEANUM, Wolle. 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 granularly rough, inter- 

 mediate area smooth or punctate; end view oval with a 

 granular tumor on each side, and two somewhat converging 

 series of teeth or aculei extending from end to end. 

 Diameter 75 yw. ; length 100 yu. 



