40 DICTYOSIPHON. 



Near low-water mark, growing on rocks or Alga. Annual. Summer. 

 Frequent on the shores of England and Ireland. Jersey. — Fronds solitary 

 or tufted, (3 — 24 inches in length, (iliforni, either pretty regularly dichoto- 

 mous, or alternately branched ; the branches forked. Ramuli more or 

 less abundant, irregularly scattered. Apices acute or acuminate. The 

 warts oi fructification densely cover the whole frond, giving the branches 

 a beaded appearance. When young the frond is solid, but in advanced 

 age, owing to the decay of the central strata of cells, it becomes hollow. 

 Substance cartilaginous, dissolving into a slimy jelly if macerated in fresh 

 water. Colour, a yellowish or olive-brown. 



2. S. Lynghyei, J. Ag. ; frond tubular, at length distended, 

 much branched, the branches dichotomous, spreading, with 

 wide, rounded axils, much attenuated towards the apices ; 

 ramuli scattered, forked, capillary ; sori subdistant, disposed 

 in transverse lines. Harv. PJiyc. Brit. /. ccxxxvii. Spo- 

 rochnns rhizodes, /3. -paradoxa^ Ag. i. Harv. Man. 1 ed. p. 

 27. Chordaria paradoxn, Lyngh. t. 14. Striaria Grevil- 

 liana, Polle.vfen MS. 



Dredged, generally on a muddy bottom, in 4 — 10 fathom water. An- 

 nual. Summer. Land-locked bays on the coasts of Scotland and Ireland, 

 abundant in many places. — Fronds from two to four feet long or more, 

 forming large tufts, or spreading, in society, over wide spaces, excessively 

 branched, nearly regularly dichotomous, tapering to a capillary fineness 

 towards the apices. Substance membranaceous, at first crisp ancl very fra- 

 gile, becoming soft in a short time. Colour, a pale olive-brown, or foxy, 

 becoming greenish olive in drying. 



VIII. DiCTYOsiPHON. Grev. [Plate 7, D.] 



Root a small, naked disk. Frond filiform, tubular, 

 branched ; its walls composed of several rows of cells, of 

 which the inner are elongated, and connected in longitudinal 

 filaments ; the outer small, polygonal, forming a membrane. 

 Frnclijication : solitary or aggregated naked spores, scat- 

 tered irregularly over the surface. Name, ^iktuov, a net, and 

 (Ti(puv, a tube ; from the tubular, reticulated frond. 



1. D. foeniculaceus, Huds. ; Grev. Aly. Brit. p. 56, t. 8 ; 

 Hook. Br. Fl. n.p. 279 ; Wyatt, Aly. Damn. No. 205. 



Between tide-marks, on stones, or parasitic on other Algae. Annual. 

 Spring and summer. All round the coast. — Fronds 1 to many feet long, 

 tufted, very much branched and bushy ; the main stem nearly a line in 

 diameter, undivided, bearing through its whole length alternate, elongate, 

 cai)iUary liranches, which again bear a second and a third series, each more 

 slender than the last, and all tapering at the extremity. Fructijicution rare. 

 Colour yellowish olive or rusty brown. 



