90 DESMIDS OF THE UNITED STATES. 



The only locality from which I had this form is Nebiaska 

 Notch, Vt., from collections made by C. G. Pringle. It 

 differs from the typical, arctic (Spitzbergen) form in its 

 greater proportionate length. 



C. PULCHERBIMUM, Xord. Plate XLIX, figs. 25-27. 



Cell? oblong, ends rounded, about one-third part longer 

 than broad, margins crenulate, constriction deep, sinus narrow- 

 linear, not ampliated towards the mouth ; semicell subsemi- 

 circular, inferior angles square, basal centre inflated and 

 .furnished with about live vertical series of granules; lat- 

 eral view broadly ovate, end rounded, and base of each side 

 more or less inflated ; membrane granulate near the margins, 

 granules arranged in about four to five concentric series; area 

 nude between these and the vertical series. 



Diameter 33 fi. ; length 10 p. 



This desmid is proportionately Bhorter than the typical 

 forms described by Dr. Nordstedt The one from Brazil and 

 the other from the island of Spitzbergen, which measure one 

 and one-third to nearly twice as long as wide. My specimens 

 are from Minnesota, and from several localities of eastern 

 Pennsylvania. 



C. radiosi m. Wolle. Plate XIX, figs. 21, 22. 



Cell.- orbiculate, about one-eighth longer than broad ; semi- 

 cells semicircular, separated by a deep narrow linear sinus; 

 ends round or slightly depressed, clothed with semiorbicnlar 

 granules arranged in about thirty-five radiating line-; basal 

 inflation has about eight vertical, or somewhat diverging 

 series of granules j lateral view subrectangular oblong; end 

 view elliptic with central inflation. 

 Diameter 50 /i.; length oi;-5<s u. 



Sluggish waters, Northampton Co., Pa. 



Genua, TETMEMORUS, Ralfs. 



Cells cylindrical or fusiform, -lightly constricted in the middle, 

 narrowly incised at each end, but otherwise entire. Cytioderm 

 mostly punctate or granulate. 



The cells are elongated as in Penivm, from which, however, this 

 genus may be distinguished by the incised end- and by the central 

 constriction. 



