desjMidium. 25 



Yar. GRACiLESCENS, Nord. 



Wittrock aud Nordstedt have, in their series of Algw exsic- 

 catce, No. 367, a small variety under this name. It is very 

 small, but the features are those of the typical plant. It was 

 collected in Brazil. The same small form occurs here ; have 

 memorandum of it from LongAvood Pond, and Wood Lake 

 of northern New Jersey. 



B. GEACILESCENS, Nord. Plate XLVII, iigs. 13, 14. 



This form is described as a variety of B. BrebissoniL 

 Whether viewed as such or as a distinct species, it was an 

 interesting discovery to find it fruiting freely in a pond near 

 Winter Park, Florida. 



Diameter of cells 14 yU ; length 23 p. ; zygospores 15 yu. 



The plant conjugates not like one of the Desmidiew, but 

 more like a Zygnemacew, in longer or shorter series ; often 

 when the zygospores are nearly matured, the cells of one side 

 separate and cause the other side to bend backward. 



Judging by these specimens the correctness of the generic 

 position of Bambusina may be questioned. 



B. DELicATissiMA, Wolle. Plate I, figs. 22, 23, 24. 



Cells sub-cylindrical, surrounded in the middle by two 

 narrow, thick bands, twice the diameter of the cylindrical 

 body, cells four times as long as wide. 



Diameter of body, 6-8 yw. ; of bands, 13-17 p. 



Pond, Pleasant Mills, New Jersey. 



The characteristic features of this plant are the small size, 

 the cylindrical form of the body, the elevation of the bands 

 which surround it, and the elongated proportion of the body. 



Genus, DBSMIDIUM, Ag. 



Plate II, figs. 1-14 ; Plate III, figs. 1-4. 



Filaments fragile, elongated, triangular or quadrangular, regu- 

 larly twisted, two chlorophyl masses in each cell barely touching 

 in the middle. Margin of cells incised or entire.. •. 



D. CYLINDEICU3I, Grev. (Didymoprium GrevilUi, Kg.) Plate 



III, figs. 1-4. 



Cells about half as long as broad, with a thickened border 



at their junction, medianly more or less deeply incised ; 



transverse view elliptic, with the angles somewhat drawn 



out. Filaments surrounded with a mucous sheath. 



