Plate XXI; Figures 134 to 144; Magnified iooo 



Diameters. 



Figs. 134, 135. Staurastrum Ravenelii Wood (?) page 62 



Fig. 136. Staurastrum furcigertim Jreb. 



Figs. 137-142. Staurastrum species undetermined 



Fig. 143. Staurastrum iotanum Wolle . . " " 



Fig. 144. eustephanum Rail's . " " 



