162 DESMIDS OF THE UNITED STATES 



The latter was collected in Minnesota; the others occur 

 frequently in small ponds and ditches, New York, (Bailey ; 

 Ehrenberg) ; Pennsylvania, New Jersey, South Carolina, 

 Massachusetts. Figs. 4-6 may represent a new species ; it 

 needs further verification. 



ST. SENARIUM, (Ehrb.), Ralfs. Plate LXIII, fig. 1. 



Smooth, each semi-cell furnished with fifteen processes j. 

 in end view triangular, each angle a process, two on each 

 side, and six radiating, on the upper surface within the 

 margins. 



I have found no form to answer this description satisfac- 

 torily. Ehrenberg and Bailey report it from New York. 



ST. PSEUDOFURCIGERUM, Reinsch. Plate LXIII, figs. 27, 28. 



Cells smooth ; semi-cells broadly elliptic, sides produced 

 into a short, stout process, with margins smooth and apicea 

 bifurcate ; end view triangular ; one process at each angle, 

 and two near the margin of each side, extending beyond it, 

 making nine processes to each semi -cell. 



Diameter 37-40 p. 



Minnesota. 



I am aware that this name is usually applied to a different 

 plant, which has a granular cytioderm and margins undulate- 

 serrate. Reinsch's figures indicate an absolutely smooth 

 membrane, and in his description he writes membrana glabra. 

 Satisfied I have Reinsch's prototype in size, and detail of con- 

 struction, it is but just to retain the name given by him. The 

 plants generally recorded for jiseudofurcigenim would prob- 

 ably be better placed with St. eustephanio/i. 



ST. CUNEATUM, Wolle. Plate LIX, figs. 7, 8. 



As long as wide, divided by a deep constriction into two- 

 broadly cuneate semi cells; base convex, broad; sides, each 

 with three to six sharp teeth, converge from the base to a 

 concave-truncate end ; superior angles somewhat produced, 

 making a short process, apex bifid or trifid; end view tri- 

 angular, sides slightly convex, angles bisected ; on the top 

 six processes radiating from the center and extending to, or 

 slightly over the margins. 

 Diameter 44-46 //. 



Ponds, Pennsylvania. 



In front view, this form bears much similarity to a plant 

 found on the Island of Spitzbergen and named St. meyalono- 

 tum, Nord., but in end view it is entirely distinct. 



