BATRACHOSPERMEiE. 63 



TABLE OF TDE NORTH AMERICAN GENERA. 



Sub-Order I. Batrachosperme^ ; Frond filamentous, gelatinous, externally clothed 

 with minute articulated ramelli. 



I. Batraciiospermum. Frond nodose, ramelli whorled. 



Sub-Order II. Lemanie^e. Frond cartilaginous, solid or hollow, with a cellular 

 peripheric stratum. 



II. Tuomeya. Frond solid, with a filiform, nodoso-articulate axis. 



III. Lemanea. Frond hollow. 



I. BATRACHOSPERMUM. Both. 



Root discoid. Frond filamentous, gelatinous, branched, consisting of an articulated 

 longitudinally striated axis beset with closely placed whorls of moniliform, free ramelli. 

 Fructljicatlon, globose clusters of seriated spores, attached to the ramelli. In fresh icatcr. 



Widely dispersed plants inhabiting clear fresh-water streams and wells in most parts 

 of the world ; rarely found in stagnant waters. Several species have been described, 

 but the characters of many are unsatisfactory. All are exceedingly gelatinous, every 

 part of the frond being invested with a clear, rather firm mucus, and when removed 

 from the water the collapsed branches have the colour and general aspect and feel of 

 frog-spawn; whence the generic name. Kiitzing, in Plate 8 of his Phycologia Gene- 

 Valis, has given figures to illustrate the early development and gradual formation of the 

 frond. At first the young plant consists merely of a string of moniliform cells. Soon 

 there is a distinction into an axis and ramelli, the axis consisting of a series of long, 

 pellucid cylindrical cells, placed one above the other ; and the ramelli being more 

 coloured, formed of roundish cellules, and placed at the nodes of the axial filament, 

 round which they gradually form a whorl. At first these ramelli are simple ; after- 

 wards they are repeatedly dichotomous. The axis in the young plant consists merely 

 of a string of naked cells ; in the full-grown frond it is invested with a sheath or outer 

 coat formed of slender filaments which issue from the bases of the whorled ramelli, 

 growing downwards like roots, adherent to the axis and continued to the next node. 

 These give the longitudinally striate appearance to the axial filament ; and in old fronds 

 they constitute the axis itself, which then becomes tubular, from the absorption or 

 rupture of the primordial tube. 



] . BATRACHOSPERMUM moniliforme, Roth. ; frond irregularly much branched, very 



