STAURASTRUM. 151 



St. enorme, Ralfs. Plate XLI, figs. 19-25. 



Cells irregular or quadrate, spinous ; end view three or four 

 lobed ; lobes broad, more or less emarginate or bifid, and 

 terminated by spines which are either simple or branched. 



Ralfs, the author of this species, says of it, it "is by far the 

 least symmetrical plant in this family, expecially in front view, 

 and it is very difficult to tract- any division into the cells." 



Some of the forms, as figs. 2 1. 25, may properly belong to this 

 genus, but the others would be better placed under Polyedrium. 

 These forma occur frequently in ponds of New Jersey, 

 P< ansylvania, Massachusetts. 



St. lepta< wtium, Nbrd. 



Var. TETROcrrocERUM, Wolle. Plate LI. figs. 29, 30. 



Cells about as long as broad; deeply constricted ; semicells 

 suborbicular furnished with eight long thin ray-, deeply forked, 

 or clawed at the end- ; this whorl is rather below the middle, 

 and another above it with four similar rays; end view octan- 

 gular, each angle produced into a lou-. thin ray, deeply clawed 

 at the end : between the margin and the centre four more 

 similar rays go out : membrane -mootli. 



Diameter of body 25 ".: including the processes 75-80 ft. 



Pond near Malaga, N. J. 



The only essential distinction between this form, and the 

 typical, Brazil plant, is that it has gix rays in the larger 

 whorl, and our- lia> eight 



St. PoTTsn, Wolle. Plate LI, figs. 8, 9. 



Small, smooth, sinus gaping : semicells in front view broadly 



elliptic, furnished on each side with three divergent processes, 

 whose apices are rounded, bearing two-mall diverging aculei ; 

 end view triangular, sides concave, angles broadly truncate 



and produced into two processes with a wide, rounded sinus 

 between, a third process from a position somewhat back of the 

 sinns, rising at an angle of about 40 degrees, projects between 

 the other two, thus constituting three divergent processes at 

 each of the angles of the triangle. 



Diameter, including the aculei 30-38 ft. 



Collected by Ed. Potts in Harvey Lake, near Wilkesbarre, 

 Pa., where it appeared in numbers. 



The three diverging, acu lei-tipped processes at each angle 

 make this form a distinct species. 



