132 . ECTOCARPACEiE. iv. 



venture to introduce it into this work, though I have not received it from any- 

 correspondent in America. 



Myeionema strangulans, Grev. ; patches convex, confluent, brown ; vertical fila- 

 ments clavate, densely set ; spores obovoid, on short stalks, attached to the decum- 

 bent filaments. Grev. Crypt. Fl t. 300. Harv. Phyc. Brit. t. 280. J. Ag. Sp. 

 Alg.l, p. 48. Kiitz. Sp. Alg. p. 540. 



Hab. Parasitical on the fronds of TJlvce and Enteromorphce ; common on the 

 shores of Europe, (v. v.) 



This parasite first appears like a dark brown stain, spotting the plant on which 

 it grows, and at this stage consists of little more than an imperfect membranous 

 expansion, composed of prostrate filaments. Afterwards, by the growth of the 

 erect filaments, the spots become convex and gelatinous, and the plant is matured. 

 The spores are of large size (for the plant), and arise, like the vertical filaments, 

 from the upper face of the decumbent ones. 



M. Ledancherii, and M. punctiforme are, with the preceding, probably to be found 

 on the American shores. 



Order YI. ECTOCAHPACE^. 



EcTOCAKPEiE, C. Ag. Sp. Alg. vol. 2, p. 9- (exd. gen.) Harv. Man. Ed. 1, p. 38. 

 Ed. 2, p. 52. Kiitz. Sp. Alg. p. 449. i^CTOCARFEJK and Sphacelaeie^, J. Ag. Alg. 

 If edit. p. 26. Sp. Alg. vol. l,p. 6, 27. Dne. Ess. p. 33, 42. Kiitz. Phyc. Gen. p. 

 287, 291. Ectocaepid^, (in part) and SPHACELAEiDiE, Lindl. Yeg. Kingd.p. 22. 



Diagnosis. Olive-coloured, articulated, filiform seaweeds, whose spores are 

 (generally) external, attached to the jointed ramuli, or formed in a swelling of the 

 ramulus. 



Natueal Chaeactee. Root commonly a small disc, or point of attachment, 

 occasionally accompanied by woolly fibres. Frond filiform and slender, {ov fila- 

 mentous) often capillary, or of extreme tenuity, more or less conspicuously articu- 

 lated, each articulation composed either of several cells of equal length disposed 

 in a ring round an axis, or of a single cell. In the latter case the frond is said to 

 be a filament (filmn, Ag. trichoma., Eg.) and is formed of a series of cells, placed 

 end to end, and strung together. In some of the higher forms, as in Cladostephus 

 and Chcetopteris, the main stem and the larger branches are inarticulate, formed of 



