CusHMAN : Zygospores of desmids 227 



Figure ij shows the completed zygospore of the same species. 



Lat. cell, c, sp. 38//, s. sp. 32 /i, lat zyg. s. acul. 32//, lat. 



zyg. c. acul. 2^ /^. 



This species was very common in a fruiting condition at South 



Framingham, Mass. 



Staurastrum brevispinum basidentatum var. nov. Plate 8, 



FIGURE II. 



Differs from the typical form in having three teeth at the base 

 of each semicell. The zygospore is much like that of the usual 



{M ^3) 



M 



Staurastrum dilatatum Ehrenb, Plate 8, figure 14. 



The small specimen here figured seems best referred to this 

 species. The zygospore is elliptical, covered with rounded pro- 

 tuberances. Whether this was the completed form of the zygo- 

 spore or not was not fully determined. 



Lat. cell. 22 /i, long. zyg. 28//, lat. zyg. 22 [i. 



r 



This small species was found in a fruiting condition at Read- 

 ing, Mass. 



Staurastrum grande Bulnh. Plate 8, figure 17. 



Figure ij represents the typically punctate form of this species. 

 The zygospore is large, angular, with broad, often somewhat 

 curved spines, scattered sparsely over the surface. As far as I 

 am aware the zygospore of this species has not been figured. 



Lat. cell. 65-85//, lat. isthm. 12-14//: lat. zyg. s. sp, 60 [x^ 

 lat zyg. c. sp. loo/i. 



Found occasionally in the collection from Reading, Mass. 



Staurastrum grande glabrumvar. nov. Plate 8, figures 15, 16. 



This variety is much like the typical form, except that it is 



entirely smooth, lacking the punctate character of the former. It 



IS slightly smaller than the typical form and is at once distinguished 



from var. rotundatum W. & G. S. West which differs from it in 

 shape. 



The zygospore of our variety is considerably different from 

 that of the typical form. It is of about the same size, but much less 

 angular and more densely set with shorter and more slender spines. 



