i osm \uir\f. 67 



or less pyramidal, base somewhat reniform, end broadly trun- 

 cate; angles rounded, cytioderm smooth or finely granulate. 

 Diameter 22-28 //. 



Ponds of eastern Pennsylvania. 



( '. indii.a n\\i, Corda. Plate XVI, fig. 2o. 



('ells 1 J times as long as wide, ends broadly rounded, 

 margins undulate ; deeply constricted, sinus gradually en- 

 larged outwardly ; semicells semiorbicular : sides and hack 

 broadly rounded, margins undulate crenate, usually with nine 

 crenae t< a semicell ; cytioderm smooth. Zygospores spheri- 

 cal, armed with long Bpines l>i- or tri-fid at apices. 

 I diameter 40-4-4 ". 



Var. creni latum, Wolle. Plate X Y I . ti-~. LO, 19, is usually 

 -mailer in size and numbering t'H to fourteen crenae to a semi- 

 cell. This variety is near < '. crenccbum but is separated by the 

 rounded ends. The typical form is from South Carolina and 

 Rhode Island, (Bailey); the variety from ponds, eastern Penn- 

 sylvania and New Jersey . 



('. CRENATUM, Kails. Plate XI A X. figs. 31, 32. 



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

 constricted in the middle; semicells crenulate at the mar- 

 gins, flattened at the end- ; generally have twelve or fourteen 

 crenae; cytioderm punctate. Zygospore globose, studded with 

 protuberances which terminate with a divided apex. 



Diameter 30-38 >>.. 



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

 Nut frequent hut occurs every now and then. 



( !. Naegelianum, Breb. \(\ orenatum, Naeg). Plate L, fig. 21. 



Small, sumewliat longer than broad, sinus narrow linear ; 



semicells, with sides sinuate-crenate, converging from the broad 



Hat base to the broadly truncate, entire or imperfectly quadri- 



erenate end-; cytioderm finely granulate or smooth. 



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



Not rare. Bears some resemblance to C. orenatum in 

 front view, but is smaller and proportionably much shorter; 

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

 of the ends imperfectly developed. 



