STAURASTRUM. 137 



Diameter 33-55 //. Not frequent. 



The figures on Plate LXIII, represent a form noted as va- 

 riety Xotarisii, Rab. Collected in ponds Barnber and Brown's- 

 Mills, N. J. 



ST. PANICULOSUM, Wolle. Plate LII, figs. 39, 40. 



Cells hexangular, as long as broad, membrane punctate; 

 punctules in radiating lines; semi-cells truncated triangles, 

 angles rounded ; inferior angles furnished with two short, 

 straight aculei ; end view triangular with one small aculeus- 

 visible on each rounded angle; sides moderately convex. 

 Diameter 40-50 /<. 



Marsh pools, near Bethlehem, Pa. 



ST. BIENEANUM, Eab. Var. ellipticum, \Ville. Plate LIII, figs. 



1,2. 



Semi-cells elliptic; end view triangular with anglea 

 rounded, sides more or less deeply concave ; membrane 

 finely punctate, distinctly observable when the cell is empty; 

 punctules regularly arranged in transverse lines. 

 Diameter 33-38 //. 



Not numerous, but hitherto found specimens in Minnesota, 

 Massachusetts, New Jersey, Pennsylvania and Florida. 



ST. INCONSPICUUM, Nord. Plate LXIV, figs. 4, 5. 



Small, about equal in length and breadth ; very indis- 

 tinctly or not at all constricted in the middle ; semi-cells 

 subquadrangular, ends usually slightly retuse; superior 

 angles produced obliquely into a geniculate arm with a 

 truncate end ; end view four radiate, sides concave. Mem- 

 brane smooth or finely punctate. 

 Diameter 14-16 /<. 



Occasional in ponds, New Jersey. 



ST. PSEUDOPACHYRHYNCHUM, Wolle. Plate LXII, figs. 32-35. 



Small, smooth or imperfectly punctate, slightly longer 

 than broad, deeply constricted ; sinus wide, base rounded ; 

 semi-cells subcuneate; from a narrow base somewhat undu- 

 lately widened to the broad, subtruncate end ; angles rather 

 broadly rounded, with a slight constriction near the apex. 

 End view tri- or quadrangular; sides sinuate. Isthmus 

 about one-fourth the diameter of cell. 



Diameter 20-24 ^. ; length 22-25 ^. 



