Mr. HassalFs Notices of British Freshwater Alga, 183 



establislied, the investing membrane is observed to be thickened 

 considerably, pointing out to the observer those cells which either 

 have, or are about to take on, the characters of reproduction. 



At one time I thought that the branches which I have so often 

 met with were spurious, and might have been formed in the same 

 manner as they sometimes are in M. genuflexa, &c., viz. by the 

 union of the extremities of certain filaments at right angles with 

 the cells of other filaments ; but this idea was dispelled by ob- 

 serving, that in the specimens in which the branches occun'ed 

 most abundantly, no union of cells in the regular way was to be 

 met with. 



The colour no less than the condition of the endochrome varies 

 considerably in this species. In some specimens the filaments are 

 of a bright green, in which case they have always been found im- 

 mersed in water ; while in others, and more frequently, they are 

 purple; which they invariably are when found spreading over 

 swampy heaths. Specimens of a beautiful green colour were re- 

 cently sent me by Mr. Jenner and Mr. Ralfs, and these for some 

 time puzzled me exceedingly. 



Notwithstanding that I have thought it right to place C. eri- 

 cetorum in the genus Mougeotia^ it yet must be acknowledged 

 that it differs in several respects from the other species of the ge- 

 nus : thus it differs in its habit and in its persistent vitality, which 

 enables it to live under circumstances which would be fatal to the 

 vast majority of Confervse, such as exposure to drought and heat ; 

 it difi'ers also in the occasional presence of ramuli on the filaments 

 and in the transference of the endochrome ; but all these differ- 

 ences are, I think, only of specific value, and are more than out- 

 weighed by the correspondence in the important fact of the non- 

 formation of sporangia. 



I have no hesitation in referring to this species the C, purpu- 

 rascens of Carmichael, which is but an aquatic condition of the 

 plant, and strongly suspect that Conf. tortuosa, Dillw. (the Zyg- 

 nema littoreum, Lyngb., and C. perreptans, Carm.) might be re- 

 ferred to it likewise. 



Nov. gen. Staurocarpus. 



Gen. char, — Sporangium either square or cruciform, and lodged 



in the transverse tubes. 



Certain square or cruciform species of conjugating Confervse 

 were doubtfully associated by Agardh with the genus Mougeotia ; 

 these species I learned long since had been separated from it by 

 Mr. Shuttleworth under the appropriate generic appellation of 

 Staurocarpus. Mr. Shuttleworth however did not, so far as I can 

 learn, publish his opinion of the propriety of estabhshing for these 



