DOCIDIUM. 53 



D. Baculum, var. Ploeidense, Wolle. Plate XII, fig. 5. 



Differing from the typical form, having the margins wavy 

 from base of semi -cell to apex. 



Diameter 15 -17 /<. ; length of cell often thirty times greater. 

 Frequent in pond near Maitland, Florida, March, 1885. 

 Probably the same as the next following. 



D. Ehkenbeegii, Ealfs. Var. Ploeidense, Wolle. 



Differs from D. Trabecula, Naeg., described, page 2, and 

 from the typical form of D. Ehrenbergii, of Ealfs, Delponte, 

 and others in its more slender cell, and in the larger number 

 of umbonations. Cell twenty or more times longer than 

 broad ; medianly distinctly constricted, without an evident 

 suture or projecting rim. Semi-cells tapering slightly, in 

 direct lines from the center to the end, with not only one or 

 two inflations (umbonations) at the base, but four, five or 

 more, often extending in slight undulations to near the end ; 

 apex squarely truncate, bordered by three to five minute 

 tubercles. 



Diameter 16-20 yu. ; length 300-400 yu. 

 Cypress Swamp, Florida. 



D. COEONATUM, Eab. Plate XIV, figs. 9, 10. 



Cells stout, cylindrical, slightly tapering from middle to 

 ends; suture projecting on each side; semi-cells inflated at 

 the base and bordered by one or two rows of tubercles at the 

 apex, which produce a crenulate appearance. 



A smaller form has the suture imperfectly developetl. 

 Vacuoles, with active granules, are usually large and dis- 

 tinct. 



Diameter 22-56 ia. 



Ponds, Pennsylvania, New Jersey, Massachusetts. 



D. OOEONULATUJI, Grun. Plate LXIV, fig. 16. 



Smooth or finely punctate, subcylindrical, slightly attenu- 

 ated near the ends; apices truncate, ornate with a crown of 

 pearly teeth. Twelve times as long as broad. 

 Diameter in middle 38 /a. Xear the ends 33 //. 



The original form of this species was found in the East 

 Indies ; the plant was somewhat thiclier, but of about the 

 same proportionate length, and so near otherwise, I adopt 

 the name. Collected it in northern New Jersey ; found the 

 finest specimens in Green Pond, commonly several united ; 

 had as many as ten cells in a series. They are without a 

 suture, and apparently without vacuoles. Found the same 

 in Florida. 



