62 BATEACHOSPERME^. 



streams) on wliich it grows. The plants rcferi-ed to this Order naturally group 

 themselves into two suborders, distinguished from each other by the habit of the frond, 

 liut closely related in structure and fructification, and as it seems to me inseparably 

 connected by the genus Tuomeya, which unites in itself the characters of the seemingly 

 so dissimilar genera Batrachospermum and Lemanea. In the first suborder (Batra- 

 chospermece verce) the branching filiform frond consists of a solid axis, invested with a 

 gelatinous coating, and composed of vertical, confervoid filaments, strongly glued 

 together. This axis is either, as in Batrachospermum, whorled at short intervals with 

 moniliforra ramelli, formed of globose cellules strung together ; or else, as in TItorea, 

 it is uniformly clothed with a villous stratum of byssoid ramelli, formed of cylindrical 

 cellules. The fructification, so far as known in this suborder, consists of globular, very 

 dense tufts of spore-threads, similar in structure to the ramelli, but of more minute 

 size, and far more densely packed together. I question whether they be propei'ly spores, 

 probably they are rather highly developed or compound gemma3. In the second sub- 

 order, Lemaniecv, the frond is denuded of confervoid ramelli, and consists altogether of 

 a compound, filiform axis, composed of minute cells. In Lemanea the frond is hollow 

 and tubular, the walls of the tube being laxly constructed within ; and moniliform 

 strings of spores, similar to those of Batrachospermum, are attached to the surface of 

 the tube. This structure is almost the exact reverse of that of Batrachosper'mece, 

 where the central axis is most solid, and clothed externally with moniliform filaments. 

 In Tuomeya the frond has at first the external characters of a Lemanea, but is furnished 

 with an axis having the structure of a Batrachospermum, as if a Batrachospermum 

 were developed within the tube of a Lemanea ; and when fully developed the surface is 

 uniformly coated with minute filaments, as in Thorea. 



Authors differ much in their views of the proper limits of this Order. Decaisne 

 unites with it Liayora and Dichotomaria (Galaxaura) both of which are undoubtedly 

 Rhodosperms ; aiul Myriocladia, which is a Melanosperm. Kiitzing separates Batra- 

 chospermum as the type of an Order of which it is the only genus ; while he refers 

 Galaxaura, Actlnotrlchia and Lemanea to his Lemaniese ; and places Thorea with his 

 Cha3tophoridese. My own views more nearly correspond with those of Mr. Berkeley, 

 who brings Batrachospermum, Thorea, and Lemanea together into one Order. These 

 genera are exclusively tluviatile or lacustrine, so far as I am aware. The marine 

 variety '■'' purpurascens," Roth, of Batr. moniUforme is founded on a figure of Dillenius 

 (Hist. Muse. t. 1-fig. 40j which certainly looks very like a Batrachospermum, but the 

 original specimen preserved in the Dillenian Herbarium belongs, according to Turner, 

 to Ceramium cUaphanum. The marine " Thorea. Americana" of Kiitz. is assuredly 

 not a congener with T. ramosissima, the type of the genus ; but properly referred by 

 Bory, who first described it, to Chordaria. 



Like most fresh water Algae, several of the species are widely distril)uted. Batra- 

 chospermum moniUforme is found througliout Europe in vaiious parts of Asia, in Tas- 

 n]ania and New Zealand, and in extra-tropical South America ; and B. vagum and 

 atrum, of which as yet I have seen no North American specimens, have nearly as exten- 

 sive a range. Lema7iea torulosa occurs, in Europe. 7\iomeya Jluviatilis has only as 

 yet been found in North Anu'rica, but occurs in distant localities (New York and 

 A]al)atiia) and may probal)]y be found to have a much larger area of distribution. 



