76 DESMIDS OF THE UNITED STATES. 



vex sides ; ends more or less truncate ; membrane smooth ; 

 end view oval ; side view circular. 

 Diameter 40-55 //. 



Springs and ponds, Pennsylvania and New Jersey. 



Fig. 47 represents a small form found in a pond on Mt. 

 Everett, Mass., measures only 29 /u. diameter. The smaller 

 size, straight sides, and more broadly truncate ends may 

 prove it to be a different species. I note it provisionally a 

 variety of the typical plant. 



C. SPHALEROSTICHUM, Nord. Plate XLVIII, figs. 26, 27. 



Cells small, somewhat longer than broad, sinus narrow 

 linear; semi-cells subreniform-trapezoid, base straight; in- 

 ferior angles nearly right ; ends in middle truncate and 

 nude, granulate, granules often in two or three vertical 

 series, often scattered, inconstant as name implies. In ver- 

 tical view elliptic, margins granulate; in lateral view cir- 

 cular, granulate. Zygospore globose or subglobose, smooth. 

 Diameter 13-14 /*. ; length 16-20 JJL. 



New Jersey and Pennsylvania. Resembles C, orthosticum, 

 Lund., but is somewhat smaller, ends truncate and granules 

 not so regularly arranged. 



C. POLYMAZUM, !Nord. Plate XIX, figs. 38-40. 



Cells about as long as wide, deeply constricted; sinus 

 narrow linear, widening somewhat outwardly ; semi -cells 

 subelliptic, margins with about sixteen crenae, and within 

 the margins a concentric series of granules to correspond ; 

 area smooth with six papillae arranged in the form of a tri- 

 angle, three in the first row nearest the margin, then two, 

 then one ; seen from the vertex, elliptical, truncate at ends, 

 with a papilla at each angle and from these two longitudinal 

 series of granules ; three papillae on each side (omitted in 

 the figure); lateral view circular, with end truncate, and two 

 rows of granules extending from the angles of the truncate 

 end of one semi-cell to those of the other; the margins of 

 the sides ornate with three papillae. 



Nordstedt made this form, found by him in Norway, a 

 variety of Lundell's C. monomazum, which has not occurred 

 here ; the other C.polymazum, is frequent in Denmark Pond, 

 N. J. 



C. OCULIFERUM, Lagh. Plate X, figs. 7, 8. 



Cells small, deeply constricted, sinus inwardly and out- 

 wardly more or less dilated ; semi-cells semicircular-trian- 



