IV. SPOROCHNACEiE.— Chnoospora. 79 



'■'■ Fi'ond flat, two feet or more long, rising with a single, undivided stem^ at its 

 base nearly cylindrical, and as thick as a crow's quill, but almost immediately 

 becoming flat, and gradually widening to the height of a few inches, where it 

 acquires a width of half an inch, or three quarters of an inch, after which it 

 becomes linear, till, on approaching the extremity, it is again slightly narrowed 

 and terminates in a rounded apex ; the margins are throughout the whole length 

 serrated with small, spiniform, rather remote teeth ; the stem, from root to summit, 

 is pinnate with opposite, distichous branches, of the same substance as itself, between 

 horizontal and patent, separated by intervals of about half an inch, a foot or a foot 

 and half long, and the middle ones, apparently, longest, their greatest width nearly 

 an inch, attenuated at their bases into very short, subcylindrical petioli, rounded at 

 their apices, toothed at their margins, and in their turns pinnated with a series of 

 others, similar to them in every particular, except their small size : — throughout 

 the whole frond runs a midrib, thick and rather wide in the stem, but in the 

 branches thin and faint, so as scarcely to be visible, unless the plant is held to the 

 light, and appearing only like a dark line. Colour grass-green, with a faint tinge 

 of bro\\m, transparent. Substance membranaceous, extremely thin and tender, but 

 somewhat thickened in the stem, near the root." 



I have not seen any American individuals of this variety, but have gathered an 

 equally broad-leaved form at the Cape of Good Hope, having, however, acute pinnae, 

 and a firmer and more coriaceous substance than Turner describes. On the whole 

 I agree with Prof J. Agardh in uniting, as one species, the broad leaved and nar- 

 row leaved forms. 



III. CHNOOSPORA, /. Ag. 



Frond compressed, repeatedly dichotomous, ribless ; its substance composed of 

 elongate prismatic cellules, scarcely denser in the centre. Fructification, densely 

 tufted, clavato-moniliform, articulated, spore-bearing filaments, surrounded by 

 sterile, branching filaments { paranemata) , both aggregated together in wartlike 

 excrescences near the middle of the frond. Spores (?) formed in the articulations 

 of the sporiferous filaments, rounded. — (J. Ag.) 



A small genus of tropical Algaj, readily known by its dichotomous branching. 

 It seems to connect together, naturally, the two sub-orders of which the Order 

 consists. In the structure of its masses of fructification there is an evident passage 

 between those genera with dispersed spore-filaments and those in which these organs 

 cohere together into definite receptacles. 



1. Chnoospoea /as%iata, J. Ag. ; "fronds tufted, several rising from the same 



