V. RHODOMELACEiE. 63 



parts, crowded on the younger, and very dense toward the extremities. These 

 ramelli are about a quarter of a line long, their lower forkings much thicker than 

 the upper, which are rather suddenly attenuated and very slender, the terminal 

 divisions much prolonged. The lower articulations of the ramelli are about as 

 long as broad, sub-opaque and multicellular ; the upper cylindrical, 4-6 times as 

 long as broad. A cross section of the stem shows five large primary tubes and five 

 alternate secondaries, surrounded by small cells. Stichidia near the base of the 

 ramelli, one on each, subsessile, oblong-acuminate, very acute, containing a triple 

 row of tetraspores. Substance exceedingly soft and tender. Colour pale red, rosy 

 toward the tips. It closely adheres to paper. 



A smaller plant than D. ramosissima, with more slender ramelli. The external 

 habit and the substance are more those of a Dudresnaia than of a Dasya. 



5. Dasta (Rhodonema) mucronata ; robust, elongate, cartilaginous, inarticulate, 

 decompound ; branches several times alternately divided, denudate, their extremi- 

 ties and the smaller branches densely clothed mth squarrose, rigid, confervoid 

 ramelli ; ramelli robust, patent, dichotomous, their axils wide and divisions divari- 

 cating, their apices remarkably mucronate ; articulations twice as long as broad, 

 dissepiments slightly contracted. 



Hab. Abundant at Key West, W. H. H. {U). (v. v.) 



Boot a spreading disc, sometimes half an inch in diameter. Steins one or more 

 from the same base, six to eight inches long or more, as thick as crowquill below, 

 attenuated upwards, simple or once or twice divided, bare of branches for an inch 

 or two above the base ; thence upwards furnished with numerous scattered or 

 crowded, alternate or irregular lateral branches. These branches are about as thick 

 as hog's bristle, 4-.5 inches Ions;, the lowest longest, and are furnished with one, two, 

 three, or more series of similar lateral branches, all of which spread at wide angles ; 

 the penultimate ones short. The larger branches are generally denuded in full 

 grown plants, but all the younger poi'tions are clothed on all sides with ramelli, 

 which are particularly dense toward the extremities. These ramelli are scarcely 

 half a line long, rather rigid, standing on the branches at right angles, and are 

 many times regularly dichotomous, with divaricating branches. The terminal cell 

 of each segment of the ramellus is very small, subulate and acute, forming a mere 

 miicro to the large oblong cell immediately below it. The articulations are uni- 

 formly about twice as long as broad. A transverse section of a branch shows five 

 large primary tulies, surrounded by a wide band of small cells. The colour of the 

 stem and branches is a dull brownish red, of the ramelli brighter and more rosy. 

 The substance is firmer and more rigid than in most others of this genus. In dry- 

 ing, it does not adhere strongly to paper. 



This species is frequently infested by parasites. It is one of the largest and 

 coarsest of the subgenus, and readily knoAvn, on microscopic examination, by the 

 mucronate ramelli. 



