32 DICTYOTACEjE. 



mentosa; of small size, more densely clothed with coloured, 

 olive or green hairs. 



On rocks and stones iu the sea, between tide-marks ; and extending, in 

 still water, to the depth of 10 15 fathoms. Annual. Summer. Fronds 

 from 1 to 20 40 feet long, scarcely twice as thick as a hog's bristle at base, 

 gradually increasing in thickness to their middle, where they are from a 

 quarter to half an inch in diameter, and again gradually diminishing to 

 the attenuated apex. Colour dark olive-brown. Substance lubricous. 



2. C. lomentaria, Lyngb. ; frond membranaceous, con- 

 stricted at distant intervals, the interstices inflated. Grev. 

 Alg. Brit. p. 48; Hook. Br. Fl. ii. p. 276; Wyatt, Alg. 

 Danm. No. 6 ; Harv. Phyc. Brit. t. cclxxxv. Asperococcus 

 castaneus, Carm. ; Hook. Br. Fl. ii. p. 277. 



On rocks and stones, between tide-marks. Annual. Summer and au- 

 tumn. Fronds 3 16 inches long, 1 4 lines in diameter, attenuated at 

 each extremity, constricted at irregular intervals into a series of bag-like 

 articulations. Substance membranaceous, flaccid. Colour a brownish or 

 yellowish olive. Asperococcus castaneus of the British Flora is the young 

 of this species: so also, according to a specimen, communicated by the 

 author, is Chlorosiphon Shuttleworthianus, Kiitz., which I formerly referred 

 to Litosiphon pusillus ; but when I made this reference I had seen no au- 

 thentic specimen of Kiitzing's plant. 



ORDER IV. DICTYOTACEJE. 



DICTYOTE^;, Grev. Alg. Brit. p. 46. J. Ag. Sp. Alg. vol. i. 

 p. 68. Endl. 3d Suppl. p. 24. Dictyoteae, Encoeliea3, and 

 part of Chordeae and Phycoserideae, Kiitz. Phyc. Gen. pp. 

 337, 336, 333, 296. Dictyotidae, Lindl. Veg. King. p. 22. 



DIAGNOSIS. Olive-coloured, inarticulate sea-weeds, whose 

 spores are superficial, disposed in definite spots or lines 

 (sori}. 



NATURAL CHARACTER. Root a disk-like expansion, some- 

 times naked, sometimes coated with woolly, jointed fibres. 

 Fronds of an olive-green or olive-brown colour, usually be- 

 coming paler on exposure to the air; of a membranaceous, 

 flexible substance, rarely coriaceous or cartilaginous, scarcely 

 at all juicy ; and of a cellular structure composed of two or 

 more strata of cells, of which the internal are usually largest : 

 the outer surface very generally having an areolated or netted 

 appearance under a lens of moderate power. In outward 



