PLATE VII. 



Fig. 1 Cosmarium conspersum. 



a, front view: /». end view: e, zygospore. 

 " 2 Cosmarium uudulatum. 



a, front view; b, end view. 

 " 3 Cosmarium leve septentrionale. 



a, front view; b, end view; c, side view. 

 " i Cosmarium rectangulare. 



a, front view: b, side view; c, end view. 

 " 5 Cosmarium broomei. 



a, front view: b, side view. 



" 6 Pleurotaeniopsis ralfsii. 



" 7 Cosmarium granatum. 



" 8 Cosmarium subcrenatum. 



" 9, side view Cosmarium subcrenatum. 



"10 Cosmarium tinctum. 



a. front view; b, side view; c, zygospore. 

 "11 Cosmarium bioculatum. 



a. front view; b, side view; c, end view. 

 "12 Cosmarium nieneghinii. 



a, front view; b, side view; c, end view. 

 "13 Cosmarium nitidulum. 



a, front view; b, side view. 

 "14 Cosmarium pulcherrimum. 



a, front view; b, side view; c, end view. 

 "15 Euastrum verrucosum. 



a, front view; b, side view. 



"16 Euastrum inerme. 



"17 Staurastrum gracile. 



a, front view; b, end view. 

 "18 Staurastrum polymorphum. 



a, front view; b, front view — form. 

 "19 Staurastrum polymorphum. 



a, front view; b, end view. 

 "20 Staurastrum crenulatum. 



a, end view; b, end view; e, front view. 

 "21 Staurastrum aristiferum 



<(, front view; b, end view. 

 "22 Mierasterias speeiosa. 



