1 14 BATRACHOSrERME^. 



ordinary beaded threads of wliich the branches are composed, 

 or as a capsule, but probably the former. It is thus seen 

 that this species is remarkable both in appearance and struc- 

 ture. 



11. Batrachospermum atrum Harv. 

 Plate XVI. Fig. 12. 



Char, Filaments very much ramified. Whorls distinct, distant, 

 short, in the form of reversed cones, oj)acj[ue ; inferior 

 portion of the articulations pellucid, 

 Lemania {batrachospermum) filamentis ramosissimis elon- 

 gatis ; nodis superne incrassato opacis, inferne alternatis 

 pellucidis, Bory, in Annales du Museum, xii. 188. Ba- 

 trachospermum moniliforme {/S) detersum Ag., Hook. 

 Brit. Flor. Batrachospermum atrum Harvo in Manual, 

 p. 120. Conf atra, E. B. t. 690. 



This species is, perhaps, the most elegant of the genus ; it 

 grows generally in still, though pure waters. Although placed 

 by Bory in his genus Lemania, it cannot be said to have 

 any near structural relation thereto. 



The articulations or internodes may be compared to re- 

 versed cones, the superior part or whorls being formed of a 

 few short, simple, subulate filaments, which are not beaded : 

 in these filaments the colouring matter chiefly resides, and it 

 is amongst them that the glomerules are formed : that portion 

 of each articulation, Avhich is below the whorl, is transparent, 

 and beautifully exhibits the tubular and jointed structure of 

 the layers which invest the primary cells in all the species of 

 the genus Batrachospermum ; from many of these tubes, short 

 branches are given off, which have almost the appearance of 

 scales. 



It is probable that there are^ several varieties of this species 

 which have all been confounded too:ether. Borv describes 

 two, both of which, I believe, I have recognised. 



a. setaceum. — Filament slender, long, ccerulescent, — 

 Bory, in Annales du Museum, xii. 188. pi. xxii. 



fig. 3. 



