16 
C. cosTATus, «. sp, (Plate xxvii., Fig, 26). — Cell ovaliform, with 
central constriction, nearly twice as long as wide; front view a con- 
stricted oval; end view circular. Constriction slight, forming an 
obtuse angle; membrane longitudinally costate; costse distinct, 5-7, 
converging at apices. Diameter of cell 50// ; length, 90//. 
In a pond, Mt. Everett, Mass. 
According to some authors, this plant might be classed with 
Docidhim; but, lacking the usual inflations at the base of the semi- 
cells, it is more properly placed as above. 
DOCIDIUM, Breb. — D. verrucosmn^ Ralfs. Frequent in ponds, 
Mt. Everett, Mass. 
COSMARIUM, Corda, — C. galeritum^ Nord. Marshes, Penn- 
sylvania. C, speciosum, Lund., and C. pulcherrimujn^ Nord.; both 
rather rare, but they occur occasionally in ponds in New Jersey, 
Pennsylvania, Massachusetts, and no doubt in all States of the 
Union. C. spectabik, DeNtris. Pennsylvania. C. reniforme^ 
(Ralfs.) Arch In Florida, and at Minneapolis, Minn, C, grande^ 
Lund. Minnpapolis. C tithophora^ Nord., and C. DeBaryi^ Arch.; 
both from ponds, Mt. Everett, Mass. C. pyramidaium^ Breb,, var, 
stenonotti^m^ Nord. Minneapolis, Minn, 
C. TRiPLiCATUM, fi, Sp. (Plate XXVII., Figs. 8 and 8a, front and end 
views). — Cell about one-fourth longer than wide, subrectangular; 
angles obtuse; sinus between the semicells linear; margins irregu- 
larly granulate, crenate; membrane rough with larger and smaller 
granules; the larger ones arranged in series of three; three on the 
margin of each of the superior rounded angles; three within the 
margins and three near the margin, between the angles; at the mar- 
gins of the inferior angles two larger granules, and, within the mar- 
gins, a few smaller scattered granules; end view quadrangular-oval," 
two series, usually of six longer granules, on each of the longer sides; 
one series on the margin and one within. Diameter of cell, 40/i; 
length about 50/^. Sporangium spherical, with long spines, acute at 
the ends. 
Ponds, Pennsylvania and New Jersey. 
The nearest approach to this plant is C Ungertanum^ N^g. It 
differs in its smaller size, the details of outline, and arrangement of 
the longer granules. 
C. Seelyanum, n, sp. (Plate xxvii., Figs. 14 and 14a, front and 
end views.) — Cell small, quadrangular, deeply constricted; sinus nar- 
row, linear; semicells twice as wide as long, with a small rounded 
notch in the middle of the sides; the superior angles slightly produced 
laterally; ends in middle about half the breadth, somewhat produced 
and crenated; membrane at the superior and inferior angles, and 
near the margin of the ends, with 3 or 4 granules. Diameter of 
cell, 25/i-3o/£. 
Frequent in a pond at Elmira, N. Y. 
C. Eloiseanum, n. sp. (Plate xxvii., Figs. 7 and 7a.) — Cell 
rather large, one-third longer than wide; constriction forming a deep, 
linear, outwardly widening sinus on each side; semi-cells semicircu- 
lar, margins set with long pointed teeth or aculei; centre inflated 
and granularly rough, intermediate area smooth or punctate; end 
