126 DESMIDS OF THE UNITED STATES. 



St. striolatum, Naeg. Plate LI, figs. 27, 28. 



Small, as broad as long, sinus acute angled; semicells ob- 

 verse reniform ; angles rounded, -ih1 concave, transverse striate, 

 five or six striae distinct on eacb lobe; end view triangular, 

 angles rounded and sides concave; each lobe transversely 

 striate. The stria' arc series of smaller or larger granules. 



Diameter 2235 ;>.. 



Not frequent, but found occasionally in distantly separated 

 localities, New Jersey, Pennsylvania, Smith Carolina, and 

 other Stat' - 



St. tricorne, Breb. Plate XLI, figs. 36, 37,38. 



Cells rough with puncta-like granules; semicells tapering 

 on each side into a -hurt, blunt, mostly entire, process ; end 

 view with three or tour blunt angles. 

 Diameter 22-28 a. 



Not in so many localities, but often numerously clustered 

 together ; Pennsylvania, New Jersey. 



St. crenattjm, Bailey. Plate XLI. figs. 5, 6. 



Semicells cuneate; outer margins crenate; end view with 

 three truncate and crenate angles : sides concave. 



This specie- was reported by Bailey to Halt's as found in 

 Rhode Island. Probably not seen since in this country. 



St. polymobphum, Breb. Plate XLII, figs. 9, LO, 24, 25. 



Semicells in front view broadly elliptic, with sides tapering 

 into short, stout processes, ends tipped with three or four small 

 spines; membrane rough with minute, sometimes acute gran- 

 ules; end view triangular, angles truncate, or drawn out into 

 short, stout processes, ends tipped with small spines. Zygo- 

 spores orbicular, armed with elongate spines forked at the end-. 

 Diameter 25-30 u. 



Frequent in ponds and small pools. 



St. crenulatum, Naeg. (Delp.) Plate XLII, figs. 26-29. 



In front view hardly separable from the preceding; end 

 view with four, five <>r six angles, each produced into a short. 



-tout, somewhat tapering ray; ends tipped with short spine-, 

 which are sometimes merely rudimentary. 



Diameter 30 38 u. 



