A L G M. 161 



A single imperfect specimen of this plant is in the collection. The 

 above-mentioned characters sufficiently distinguish it from any other 

 member of the genus. In habit it resembles a Ptilota; but the cross- 

 section of the stem shows the structure of Dasya. The frond is seve- 

 ral inches long, ovate in outline, twice or thrice pinnate ; the pinnae 

 alternate and elongated ; the pinnules short. Both pinnae and pinnules 

 are beset throughout with short, distichous, opposite, jointed ramelli. 

 The branches are strongly compressed and somewhat two-edged, quite 

 opaque, and coated with small cells. Color, a clear carmine. 



Botryocarpum platycarpum, Kutz. ; Harv. Ner. Bor. Am. 2, p. 100. 



Hymenena fissa, Grev. ; Harv. I. c. p. 101. 



Hymenena fimbriata, Post & Ruppr. ; Harv. I. c. p. 102. 



Plocamium coccineum, Lyngb. ; Harv. 1. c. p. 153. 



Rhodymenia Wilkesii, Harv. & Bail. (Tab. 4.) 



R. stipite brevi cartilaginea compressa mox cuneato-plana et in laminam 

 1-%-pedalem lato-lanceolatam subindivisam rnembranaceam sanguineo- 

 rubescenturn explanata; coccidiis numerosissimis per frondem densis- 

 sime sparsis* 



Hab. Straits of San Juan de Fuca. 



Root scutate. Fronds tufted, rising with a compressed cartilaginous 

 stem ; which, at about half an inch to an inch in height, becomes 

 flattened, cuneate, and gradually widens out and is lost in the base of 

 a broadly lanceolate lamina, from one to three feet in length, and from 

 4 to 8 or 10 inches in breadth. Lamina obovate-lanceolate, much 

 attenuated at the base, entire ? or sometimes forked, commonly quite 

 simple, of a pale, sanguineous red, fading to greenish ; the newer por- 

 tion formed, as in the Laminarice, between the apex of the cartilagi- 

 nous stem, and the base of the expanded portion of the frond. Coc- 

 cidia about as large as poppy-seed, spherical, extremely numerous, 

 imbedded in the lamina, and scattered thickly through three-fourths 

 of it, commencing near the apex, and gradually extending towards 

 the base. 



* For the reasons given in the Nereis Boreali- Americana, 2, p. 147, the name of this 

 species must be changed to Rhodymenia pertusa, J. Ag. Sp. Alg. 2, p. 376. W. H. H. 



41 



