160 DESMIDS OF THE UNITED STATES. 



differs somewhat from the more northern form, in having the 

 subulate spines at the angles not so long, and the cell itself not 

 quite so large. Jas. L. Bennett reports this plant from Provi- 

 dence, B. I., with end view triangular. 



ST. LONGISPINUM, Bailey. Plate LII, fig. 7. 



Large, smooth, triangular, with two long spines at each 

 angle. 



Diameter of body 75 yw. ; with spines 150 ^. 

 Lakes in Florida (Bailey). 



ST. QUADRANGULARE, Breb. Plate LII, figs. 1-4. 



Cells smooth, nearly square, divided by a deep, linear 



constriction into rectangular-oblong semi-cells with a few 



marginal spines or teeth ; end view quadrilateral, sides more 



or less concave, angles truncate and emarginate or dentate. 



Diameter 23-30 /A 



Not infrequent in ponds of Pennsylvania, New Jersey and 

 Florida. 



ST. BRASILIENSE, Nord. Plate LIX, figs. 1, 2, 3. 



Semi-cells short cuneate, top truncate, or moderately 

 rounded, angles terminating- in three firm, diverging aculei : 

 end view pentangular ; each angle produced into three more 

 or less elongated firm subulate diverging spines, sides con- 

 cave ; membrane punctate. 



Diameter 87-130 //., including the spines. 



Three localities only have been developed for this species ; 

 Florida furnishes the smaller form figured ; the other is from 

 pond, Passaic County, New Jersey, and from vicinity of 

 Mobile, Alabama. The original form from Brazil, is described 

 by the author as usually quadrangular, and angles often 

 furnished with four spines. 



Var. TRIQUETRUM, Wolle. Plate XLIX, figs. 39, 40. 



The form hitherto found here is pentangular in vertical 

 view ; the form first discovered and described by Nordstedt, 

 is quadrangular, found in Brazil. The present variety from 

 California is triangular in vertical view ; it appears so nearly 

 related in character of cell, arrangement and character of 

 aculei, think it best described as a variety of the saim- 

 species. 



Diameter of cells, including aculei, 63-67 //. 



Smaller than the pentangular form, but about the same 

 size as the original quadrangular form. 



Collected in small pools near Lake Tahoe, by Mrs. 

 and Miss Haggin, San Francisco, California. 



