COSMARIUM. 73 



Var. CRENULATUM, Wolle. Plate XIX, figs. 10, 19, is usually 

 smaller in size and numbering ten to fourteen crenae to a 

 semi cell. This variety is near C. crenatum, but is separated 

 by the rounded ends. The typical form is from South Caro- 

 lina and Rhode Island, (Bailey); the variety from ponds, 

 eastern Pennsylvania and New Jersey. 



C. CRENATUM, Ralfs. Plate LX, figs. 31, 32. 



Cells oblong, usually nearly twice as long as wide, deeply 

 constricted in the middle ; semi-cells crenulate at the mar- 

 gins, flattened at the ends ; generally have twelve or fourteen 

 crenae; cytioderiu punctate. Zygospore globose, studded 

 with protuberances which terminate with a divided apex. 

 Diameter 30-38 /v. 



Rhode Island, New Jersey, Pennsylvania, and other States. 

 Not frequent, but occurs every now and then. 



C. NAEGELIANUM, Breb. (C. crenatum, Naeg.} Plate LXI, fig. 21. 

 Small, somewhat longer than broad, sinus narrow linear f 

 semi-cells, with sides sinuate-crenate, converging from the 

 broad flat base to the broadly truncate, entire or imperfectly 

 quadricrenate ends ; cytioderm finely granulate or smooth. 

 Diameter 20 /*., or a little more or less. 



Not rare. Bears some resemblance to C. crenatum in front 

 view, but is smaller and proportion ably much shorter ; the 

 crenae of the sides are usually less in number, and those of 

 the ends imperfectly developed. 



C. VENUSTUM, Eab. Plate XIX, fig. 3<~. 



Length of cell equal to about 1 diameters; constriction 

 deep; sinus narrow linear; semi-cells have a flat base, rounded 

 lower angles, sides somewhat convergent ; each with two 

 notches of equal size ; ends truncate, and slightly retuse. 

 One chlorophyl mass in each semi-cell ; membrane smooth. 

 Diameter 24-30 //. 



Occasional in ponds, Pennsylvania and New Jersey. 



C. EEINSCHII, Arch. (Dublin Microscopical Club. ) Plate XIX T 



fig. 12. 



Somewhat longer than broad, deeply constricted, sinus 

 narrow linear ; ends truncate ; sides convex, erose, dentate 

 or notched. Membrane smooth ; end view elliptic, without 

 a central inflation. 

 Diameter 30-35 /*. 



Not frequent, but is found in Lake Hopatcoug, N. J., and 

 in ponds, eastern Pennsylvania. 



