524 EHODOMELACEAE. 



ramification, spreading about equally broad. Its branches are more widely 

 spaced and not so obviously two-ranked. . The apices are conspicuously in- 

 rolled; monosiphonous prolongations of the ultimate branchlets occur in the 

 younger parts. The stichidia are cylindric-lanceolate, rostrate, and usually 

 4-6 times as long as broad. The blackish or violet-brown plants are ascend- 

 ing, or pendent rather than creeping. The species occurs in caverns and 

 under shelving rocks, but is at its best on roots of mangroves, growing just 

 below the high-tide mark, mostly at a lower level than B. tenella. (Alg. Exs. 

 Am. Bor. 136; Phyc. Bor.-Am. 1893.) 



Heterosiphonia Wurdemanni (Bail.) Falkenb. is a small plant, mostly 

 A-1 inch long or high, growing on other algae and on Gorgonians. The main 

 axes have 4-6 (usually 5) pericentral siphons and are uncorticated throughout. 

 These axes bear, usually at intervals of two segments, minute rather rigid 

 branchlets which are monosiphonous throughout or polysiphonous at base and 

 are several times divaricately dichotomous. These branchlets are primarily 

 2-ranked and alternate, but this regularity is sometimes interfered with by the 

 development of adventitious or secondary branchlets. The cells of the branch- 

 lets are mostly a little longer than broad. The stichidia are ovoid-conic 

 or obpyriform, about twice as long as broad, provided with a one-celled 

 apiculus, and subsessile on a pedicel that is unicellular, at least as to its 

 basal segment. (Phyc. Bor.-Am. 2097.) 



Dasya corymbifera J. Ag. is usually li-'2^ inches long and grows under 

 shelving rocks near the low-water mark. In the pressed and dried condition it 

 shows a vaguely pinnate mode of branching. The main branches, together 

 with their small, spirally alternate, monosiphonous, several times dichotomous, 

 fasciculate-corymbose branchlets, are i-1 line broad. The branchlets taper 

 decidedly and the ultimate divisions are, for the most part, strongly incurved 

 or subfalcate. The main axes are strongly corticated, and in the uncorticated 

 upper parts the segments are a little longer than broad, the individual peri- 

 central siphons being usually 3-6 times as long as broad. Cells of the branch- 

 lets are 2-5 times as long as broad. The stichidia are conic-subulate, on 

 monosiphonous pedicels 1 or 2 (rarely 3) cells long, 



Dasya Collinsiana M. A. Howe, sp. nov. Plants dingy red, often yellowish 

 on drying, forming rather dense subhemispheric tufts 1-3 cm. high, 5-8 times 

 subdichotomous, the branches corymbose or somewhat fastigiate, the terminal 

 (with branchlets) alopecuroid, and 1-1.5 mm. in diameter; main axes 0.5-0.75 

 mm. in diameter near base, densely but rather pellucidly corticated up to the 

 last two or three dichotomies; segments of upper uncorticated or lightly cor- 

 ticated parts often poorly defined owing to overlapping of siphons, varying 

 from one half as long as broad to slightly longer than broad, the five peri- 

 central siphons translucent, conspicuous, varying from slightly longer than 

 broad to 2-3 (rarely 4) times as long as broad, often subquadrate; branch- 

 lets monosiphonous, patent, divaricate, or subsquarrose, 0,5-0.9 mm. long, 4 or 

 5 times divaricately dichotomous, the lower rigid and slightly tapering, those 

 of the terminal coma softer, connivent, more tapering and often short-pilif- 

 erous; basal cells of the branchlets 100-130 /a in diam., commonly shorter than 

 broad, "the terminal and subterminal cells mostly 45-55 At in diam. (except in 

 apical coma), about twice as long as broad; stichidia alopecuroid, acuminate- 



