V. P.HODOMELACE/E. 13 



1. Amansia viulfijida, Lamour. ; stem vaguely branched, obsoletely -winged, 

 bearing numerous, irregularly placed, ovate, deeply bi-tri-pinnatifid fronds, prolife- 

 rous fi'om the midrib ; laciniie linear, with a very slender nerve ; lacinulaj broadly 

 subulate, their apices strongly inrolled. Lamour. Bull. Phil. 1809- t. 6. Ag. Sp. 

 Alg. \. p. 192. /. Ag. in Linncea. XV. p. 26. Odonthalia muldjida, Endl. 3d. SuppA. 

 p. 47. Epineuron muliijldum, Kiitz. Sp. Alg. p. 848. 



Hab. Abundantly cast up at Key West, W. H. H. &c. (v. v. ) 



Tufts much branched. Stems three to four inches long, cartilaginous, naked or 

 winged with the remains of a membranous lamina, throwing out numerous, 

 irregularly placed, leaf-like, secondary fronds, which are sometimes distant, 

 sometimes densely crowded, Avhen the plant becomes an intricate, globose 

 mass of fronds. These secondary fronds are ovate or ovato-lanceolate in outline, 

 either pinnatifid, bipinnatifid or tripinnatifid, delicately membranaceous, their main 

 rachis traversed by a strong cartilaginous midrib, which gradually becomes thinner 

 and ftiintcr upwards ; their pinna? and pinnules marked by a very fine, depressed 

 central line. The midribs of the larger branches are frcquentl}^ proliferous. The 

 apices of all the pinnute are strongly rolled inwards. I have not seen fruit of 

 either kind ; but what appear to be antheridia are very common (in February) 

 crowding around the tips of all the laciniaj, the usual position in Algaj of this 

 order : they are pedicellate, ovate, filled with minute grains. Colour a purplish 

 pink, becoming browner in drying, and soon fading in fresh water. The substance 

 is rather rigidly membranaceous, and in drying the plant does not adhere to paper. 



Endlicher has strangely misunderstood the atfinities of this plant, by placing it in 

 Odonthalia, a genus with a very different structure. 



II. ODONTHALIA. Lyngh. 



Frond flat or nearly so, thickish, subopaque, di^tichously pinnatifid, obsoletely 

 midribl)ed, the margin alternately toothed. Structure densely cellular; the surface 

 cells very minute, polygonal, irregular in size and form. Conceptacles marginal, 

 mostly axillary, pedicellate, ovate, wide-mouthed, containing a tuft of pear-shaped 

 spores. Stichidia marginal, mostly axillary, stipitate, corymbose, lanceolate, con- 

 taining a double row of tetraspores. 



This group, separated from Rhodomda by Lyngbye, has been generally received 

 by botanists, and by all but Endlicher, with nearly the same limitation. It differs 

 from Bhodomela in the nearly flattened, two-edged, broadly linear frond, the middle 

 portion of whicli is thickened into a more or less evident costa ; and in the position 

 of the fructification in axillary processes. The species have all been found in the 



