122 



Chlorophycece 



M. parvula Haws. (fig. 44 D H) and M. gracillima (Hass.) Wittr. (fig. 44 I), 

 which conjugate freely in all parts of the country and at all elevations up to 

 1,200 ft. M. genuflexa (Dillw.) Ag. is a frequent species in ditches and ponds. 

 M. gelatinosa Wittr. is one of the rarest British species, being characterized 

 by the curious gelatinous investment of the carpospore. 



Genus Gonatonema Wittr., 1878. The thallus is similar in 

 all respects to that of Mougeotia, but the reproduction is brought 

 about solely by the formation of aplanospores, the filaments usually 

 becoming genuflexed at the points of location of the spores. Each 



Fig. 45. A-F, Gonatonema Boodlei W. & G. S. West, from Mitcham Common, 

 Surrey. G J, G. ventricosum Wittr., from the river above Crolly Bridge, 

 Donegal, Ireland. (All x 445.) a, aplanospore. 





