BATRACnOSPERMUM. 103 



or are tlirown off. They would appear to partake more of the 

 natui'e of buds than seeds. When developing, each emits 

 numerous branches, Avhich radiate in all directions. 



Bory would seem to be the only observer who has studied 

 the species of this genus with that nice discrimination which 

 they require: in associating Batrachospermum atrum, however, 

 and some other species with the genus Thorca, he has 

 committed a great error. By a careful comparison of speci- 

 mens derived fiom the herbarium of Dillenius, which are 

 in the collection of M. de Jussieu, with others collected by 

 Roth, ]\Iertens, and Draparnaud, Bory has succeeded in 

 ascertaining the correct synonymes of several species or varie- 

 ties, which had previously been quoted indiscriminately. 



From the great number of specimens described in the 

 following pages, there are some, I fear, who will be dis- 

 posed to think that they have been multli^lied on insuf- 

 ficient grounds: such an opinion I ani sure will not be 

 entertained by those who have carefully studied the genus 

 for themselves, and who have had opportunities, as mainly 

 through the liberality of friends I have had, of comparing 

 a considerable number of specimens collected from widely 

 different localities together. 



I suspect that the species of tliis genus are propagated 

 not merely by gemmo3 or glomerules, but also by Zoospores, 

 contained as in other Algcs zoospo7-(B in the cells, of the 

 aggregation of which these plants are composed. 



The affinities of the genus are by no means direct, in their 

 lubricitj^, in the presence of cilia, and probably in tlieir 

 reproduction by zoospores they bear a certain relationship 

 to the family ChcBtophorccu. 



a. Filaments exceedingly jlexihle. 



1. Batrachospermum bombusinum Borg. 



Plate XIII. Fig. 3. 



Char. Frond delicate, filaments sparingly branched, branches 

 simple. Cells much elongated. Vcrticilli minute, distant. 



H 4 



