DOCIDIUM. 55 



D. WOODII, Delp. Plate XII, fig. 4. 



Cells cylindrical, six to ten times longer than broad ; 

 apices rounded ; basal inflation of semi-cell large, wide and 

 high ; cytioderni smooth. 



Diameter at ends 50 /*. : inflation 65 /<. 

 Pond, Ocean County, New Jersey. 



D. GEORGICUM, Lagh. Plate X, fig. 16. 



Cells large, twelve times longer than broad ; moderately 

 constricted in the middle ; suture none ; semi-cells much 

 swollen about the middle ; basal part with four larger and 

 smaller undulations, alternating large and small ; ends 

 somewhat attenuated ; apices roundly truncate ; membrane 

 hyaline, punctate, thickest at the ends no aculei nor teeth. 



Diameter of cells, basal parts 54 yu. ; middle 75 yu. ; 

 apices 39 yw. 



Pond waters, Georgia. 



D. DILATA.TUM, (Cleve), Lund. Plate LXI, fig. 32. 



Cells slender, cylindrical, 15-20 times longer than broad, 

 undulate-nodose ; base moderately inflated and longitudin- 

 ally plicate ; no suture evident ; semi-cells usually with 

 eight inflations and corresponding constrictions; apices 

 roundly truncate and more or less dilated. 

 Diameter 13-16 yw. 



Brown's Mills, and other ponds, New Jersey. 



D. SINUOSUM, Wolle. Plate XIV, figs. 6, 8 ; variety fig. 7. 



Slender, undulate, smooth, cylindrical ; 20-24 times longer 

 than broad ; semi-cell with eight constrictions ; ends trun- 

 cate, straight or slightly concave, each angle furnished with 

 a short, stout tooth ; basal inflation not plicate. 

 Diameter 12-14 yu. 



Var. BREVE, Wolle. (Fig. 7) only half the length, and onlj- four 

 constrictions to a semi-cell. 

 Diameter 12-14 yu. 



Very near the preceding, but armed with teeth at the apex, 

 not plicate, and sometimes only half the length. Pond, 

 Pleasant Mills, New Jersey. 



D. UNDULA.TUM, Bail. Plate XIV, fig. 5. 



Cells small, cylindrical with undulating margins, 18-20 

 times longer than the diameter ; moderately constricted in 



