32 DESMIDS OF THE UNITED STATES. 



This form was recorded with hesitation ; it was one of the 

 latest finds in the fall of 1883 ; but since it occurred frequently 

 in ponds at Brown's Mills, JIanchester and other waters, 

 New Jersey. 



Genits, MESOTAEXIUM. Xaeg. 

 Palmogloea, Kg. Plate III. figs. .5-15. 



Cells straight, sliort cylindrical, or oval, ends rounded, not 

 constricted in the middle. CJilorophyl lamina axillarj^, sometimes 

 divided in the middle. 



Copulation takes place by two cells uniting side by side, the 

 contents flowing together. 



Kirchner remarks that copulation in this genus is a simple 

 union of two cells, leaving no husks or remains of empty cells ; 

 (compare figs. .5-9 >. This process accords with my observations, 

 but Wood illustrates another mode transferred in figs. 13-15, in 

 which the contents of the cells flow together and are surrounded 

 by a new membrane ; in this case the remains of the old cells 

 are present. 



These plants occur frequently in small pools, on dripping rocks, 

 damp walls, wet ground and the like ; sometimes singly, but 

 more frec[uently associated in families in a gelatinous mucus. 



M. Bkauxii, D. By. (Palmogloea macrococca, Kg.) Plate III, 

 figs. 5-9. 

 Cells cylindrical, 2-2 J times longer than wide, ends flatly 

 rounded. Zygospore square, angles rounded, sides usually 

 somewhat concave. 

 Diameter 16-19 /(. 



Found floating, in families, in gelatinous scum, mountain 

 pools. 



M. MicRococcuM, Kg. Plate III, fig. 10. 



Cells oval or elliptical, about twice as long as wide, ends 

 sometimes slightly narrowed and rounded. 

 Diameter 6-11 yu. 



Usually in gelatinous masses on old wet wood, timbers of 

 sluices, etc. 



M. Endlicheeiaxum, Xaeg. Plate III, fig. 11. 



Cells cylindrical, 3-4 times as long as wide, ends bluntly 

 rounded. 



Diameter 9-11 /<. 



Occasionally intermingled with filamentous forms, in gela- 

 tinous gatherings. 



