64 RHODOMELACE^. v. 



6. Dasya (Riiodonema) Wiirdemanni, Bail. ; capillary, of small size, (an inch 

 hio-h), once or twice forked ; secondary branches alternate or secund, arched, arti- 

 culate hirsute with squarrose ramelli ; ramelli very patent, many times dichoto- 

 mous sub-ricid, their divisions divaricating, apices acute, articulations once or 

 twice as long as broad. (Tab. XY. C.) var. /3. dichotoma ; more regularly dichoto- 

 mous, with shorter and straighter secondary branches. 



Hab. Abundant on Algae and corals, at Key West. Dr. Wurdeman, W. H. H. 

 (15). (v. V.) 



This forms small, roundish, dense, fastigiate tufts, or often is entangled among 

 the branches of the Algaj which it infests. 



The stems are an inch or two high, about as thick as coarse human hair, once or 

 twice forked, and then alternately or secundly branched. The secondary branches 

 are very frequently secund, erect, arching inwards, with the ends inrolled, and are 

 beset throughout mth ramelli which are short and subdistant below, gradually 

 longer and more densely set above, and also longer and more numerous on the 

 outer than on the inner side of the curved branch. These ramelli stand almost at 

 right angles on the branch, are several times forked, with very wide axils and 

 divaricated segments, and their articulations are seldom more than twice as long as 

 broad. The stem and branches are obviously jointed, the internodes few-tubed 

 with pellucid nodes, but I have not been able to determine the number of tubes, 

 whether four or five, owing to the very imperfect absorbent powers of the dried 

 cells. The colour is a dull red, inclining to brown. The substance is somewhat 

 rigid, not at all lubricous. In drying, the plant adheres pretty firmly to paper. 



/3. is a little different in aspect, the stem being more regularly dichotomous, the 

 secondary branches shorter and straighter, and the ramelli more equally distributed. 

 It somewhat resembles some weak-growing forms of D. arbuscula, to which D. 

 Wurdemanni is certainly allied, although perfectly distinct. 



The specific name was bestowed by Prof Bailey in honour of the late Dr. Wurde- 

 man, who first detected this curious little species, and to whom we are indebted for 

 an interesting series of Key West Algte. 



Plate XV. C. Fig. 1, Dasya Wurdemanni; the natural size. Fig. 2, some 

 branches ; fig. 3, portion of a branch, with ramellus ; the latter figures magnified. 



Subgenus 3. Lophothalia. Frond articulate or opaque, four-tubed, virgate, 

 alternately branched ; branches naked or clothed with simple or pinnated, single 

 tubed, confervoid ramelli. Stichidia rising from the branches, hirsute with ramelli. 



7. Dasya (Lophothalia) Tumanowiczi, Gatty; stem cartilaginous, opaque, ro- 

 bust, attenuated upwards, alternately decompound; branches elongate, setaceous, 

 their divisions capillary, set with short spine-like branchlets, and imperfectly arti- 

 culated; internodes once and half as long as broad, coated with polygonal cells; 



