* In fresh water.

1. G. minutissimum, Grev.; minute, ochraceous, somewhat scattered, entangled; stipes sub-ramose; frustula linearwedge-shaped. Grev. in Hook. l. c. p. 409; Crypt. Fl. t. 244, f. 1.

Pools and lakes, on the stems of water-plants. Duddingston Loch, Dr. Greville. Spring." The presence of this plant gives a yellowish appearance to the water. The stipes is sometimes simple, sometimes once or twice divided; the frustula united or separated, hyaline at the base and apex, but containing a green, granular mass in the centre. The whole is scarcely more than a line in height." Grev.

2. G. Berkeleyi, Grev.; tufted, tawny; stipes sub-ramose; frustula wedge-shaped, truncate. Grev. l. c. p. 409. Exilaria minutissima, Berk. Alg. p. 22, t. 7, f. 1.

Attached to sticks, stones, grass &c. in fresh water, Rev. M. J. Berkeley. Spring and early summer.-" Tufts or masses several lines thick, of a tawny colour; when dry of a lively green. Mr. Berkeley thinks it may be the same as the preceding, which, however, is a much smaller plant, less tufted, and whitish or slightly ochraceous when dry. I have therefore ventured to keep it distinct." Grev.

3. G. minutum, Ag.; plant forming an apparently pulverulent stratum; stipes sparingly branched; the frustula linear-conical, globuliferous at tip. Grev. in Hook. l. c. p. 410.

Streams, attached to Confervæ &c. Appin, Capt. Carmichael.- -"Stratum, according to Agardh, having a pulverulent appearance to the naked eye when recent; the stipes branched or nearly simple; the frustula hyaline, with a green globule at the apex. The only specimens I have seen are those in a dry state, from Capt. Carmichael, and the globule is not visible. It is therefore possible that I may not be correct in referring it to this place." Grev.

4. G. geminatum, Ag. ; densely tufted, pale tawny; stipes elongated, dichotomous; frustula at first cuneate, solitary or in pairs, becoming somewhat urn-shaped. Grev. in Hook. 1. c. p. 410; Crypt. Fl. t. 244, f. 2.

On stones &c. in the beds of alpine streams and rivulets, frequent. Scotland, Dr. Greville. North of Ireland, Mr. D. Moore. Wales, Mr. Ralfs. -This forms roundish tufts, often an inch in diameter, of a soft, flaccid substance, and brownish colour. The filaments are very slender, several times forked, bearing on their tips a pair of wedge-shaped or somewhat urnshaped frustules, which are hyaline, containing a granular mass. When dry it is grey and powdery.

5. G. ampullaceum, Grev.; densely tufted; stipes elongated, dichotomous; frustula in pairs, but distinct, urn-shaped,

208

GOMPHONEMA-HOMEOCLADIA-BERKELEYA.

rounded at the apex.

Grev. l. c. p. 410. Echinella ampul

lacea, Carm. MSS. cum icone.

On rocks and stones in the river of Glenstockdale, abundant, Capt. Carmichael. Spring and summer. - Nearly allied to the last, from which it seems to differ by the more distinctly urn-shaped frustules. I have seen no specimens.

** In the sea.

6. G. paradoxum, Ag.; aggregated, yellow, very minute; stipes erect, sparingly dichotomous; frustula wedge-shaped, somewhat corymbose. Grev. in Hook. l. c. p. 410. Echinella paradoxa, Lyngb. Grev. Crypt. Fl. t. 25.

Parasitical on the smaller marine Algæ; very common. Spring and summer. - This is less than a line in height, and forms a yellowish, downy, coating to various filiform Algæ, often completely obscuring the colour of the plant on which it grows. The stipes is rarely more than once or twice

branched.

7. G. majusculum; densely tufted, yellowish-green; stipes erect, very much branched; frustules broadly-wedge-shaped, truncate, bright green (when dry).

On timber floating in the sea, at Port Rush, Co. Antrim, Mr. D. Moore. - This comes near G. paradoxum, but is a much larger plant, to an inch in length, and the stipes very much more branched; but in a dry state, in which only I have seen it, it is impossible to separate the filaments sufficiently to see how they are branched. It is green when dry.

CXXIV. HOMEоCLADIA. Ag.

Frustula arranged in numerous, binate, distant, parallel series, within a tubular frond. Ag. Name, ouolos, like, and xxados, a branch.

1. H. Anglica, Ag.; filaments tri-dichotomous. Ag. Con. Crit. p. 25; Grev. in Hook. l. c. p. 411.

In the sea. Plymouth, Agardh.--" Frond an inch and a half or more in length, tubular, terete, erect, filiform, a line in diameter at base, gradually attenuated, containing numerous, distant, parallel series of frustula, trichotomous below, dichotomous above, obtuse at the apices. Colour when dry, opaque olivaceous green. Substance firm. It does not adhere to paper." Ag.-No British botanist seems to be acquainted with this plant, and Agardh does not mention from whom he received his specimens.

CXXV. BERKELEYA. Grev.

Frustula in longitudinal series, within simple, mucous filaments, which are free at the extremity, but united below

into a roundish, gelatinous mass. Grev. Named in honour of the Rev. M. J. Berkeley, an assiduous and accomplished British botanist, author of Gleanings of British Alge,' of the article Fungi' in 'Hooker's Brit. Flora,' and of several admirable memoirs on the fructification, &c., of that extensive class of plants.

1. B. fragilis, Grev. Grev. Crypt. Fl. t. 294; Grev. in Hook. l. c. p. 416; Ag. Consp. Crit. p. 24.

Parasitical on Zostera and the smaller marine Algæ. Appin, Capt. Carmichael. Near the Land's End, Mr. Ralfs.- "Plant of a reddish brown colour, and roundish or oval form, consisting of a rather firm gelatinous mass or receptacle, less than half an inch in diameter, and a number of filaments which seem to spring from its surface. This gelatinous receptacle is firmly attached to the plant on which it grows, sometimes surrounding the small branches of Furcellaria fastigiata. The filaments are immersed for half their length in the receptacle, the extremities being free. They are gelatinous, exceedingly tender and fragile, simple, attenuated towards the apex, apparently destitute of external membrane, and containing a number of oblong or rather fusiform frustules, arranged longitudinally, but without order." Grev. Cr. Fl.- Mr. Ralfs' plant exactly agrees with a specimen in my possession from Capt. Carmichael.

CXXVI. SCHIZONEMA. Ag.

Frustula in longitudinal series or scattered, and inclosed within a simple or branched, gelatinous, mucous, or membranaceous frond, composed of one or several tubes. Name, oxicw, to divide, and vua, a thread; the branches of the typical species being formed, as it were, by cleaving the frond.

*Fronds erect, branched, robust, (Schizonema).

1. S. obtusum, Grev.; frond robust, cartilagineo-gelatinous, elastic, firm, ultra-setaceous, laxly tufted, fastigiate, many times dichotomous; axils rounded; apices obtuse; frustules minute, very numerous, oblong, binate. Grev. in Hook. l. c. p. 413; Crypt. Fl. t. 302.

Parasitic on small Algæ, in the sea. Frith of Forth, Dr. Greville. Appin, Capt. Carmichael. Torquay, Mrs. Griffiths. Salcombe, Mrs. Wyatt. Coast of Antrim, Mr. D. Moore.-Frond 2 or 3 inches high, robust, thicker than a hog's bristle, and nearly of equal diameter throughout; laxly tufted, irregularly dichotomous; the lower divisions somewhat distant, the upper closer, frequently very close, in which case they are somewhat entangled. -Substance firm and elastic. Colour yellowish green, not much changed in drying. Odour somewhat offensive. Frustules very minute, closely packed in a transparent jelly. A handsome and distinct species, well marked by the rounded axils and obtuse apices. Mrs. Griffiths finds it "dark brown" when recent; in other respects her specimens accord with the Scotch ones, and in a dry state their colour is identical.

Р

2. S. apiculatum, Ag.; frond robust, ultra-setaceous, cartilaginous, very tenacious, scattered or slightly tufted, irregularly dichotomous, sparingly divided; branches thickened upwards, suddenly acuminate at the apex; frustules very numerous, minute, green. Ag. Syst. p. 11. Micromega apiculatum, Ag. Consp. Crit. p. 23; Grev. in Hook. l. c. p. 411. Gloionema apiculatum, Grev. Crypt. t. 30.

Frith of Forth,

In the sea, on rocks in small pools left by the tide; rare. Messrs. Arnott and Greville. March.-Fronds either slightly tufted or scattered, about half an inch high, thicker than hogs' bristles, erect, very firm and tenacious, irregularly branched or dichotomous, the branches erect, with acute axils, swollen upwards, especially just below the tips, ending in a sudden point.

3. S. ramosissimum, Ag.; frond robust, setaceous at base, cartilaginous, firm, excessively branched in a sub-dichotomous manner, fastigiate; branches slender at their insertion, swelling upwards, especially towards the tip, which is suddenly acuminate; frustules very dense, minute. Ag. Syst. p. 11. Micromega ramosissimum, Ag. Consp. Crit. p. 22. Sch. apiculatum, Chauv.! Alg. Norm. (excl. Syn. Grev.); Wyatt, Alg. Danm. No. 235.

On rocks in the sea. Waldon rocks, Miss Amelia Griffiths. On the Harbrick, in Torbay, Mrs. Wyatt.-Fronds tufted, 1—11⁄2 inch high, very firm and elastic, expanding in water, very much branched. Colour, when dry, greyish olive without gloss. I have compared Mrs. Wyatt's specimens with one from Chauvin, and find them to agree exactly.

4. S. helminthosum, Chauv.; frond robust, ultra-setaceous at base, elastic, firm, much branched; branches flexuous, variously twisted, divided into many lacerated segments, capillary above; the apices acute; frustules large, rather dense, oblong. Ch. Alg. Norm. Exsicc. No. 77; Grev. in Hook. l. c. p. 412; Wyatt, Alg. Danm. No. 198.

On rocks in the sea. Frith of Forth, Dr. Greville. Torquay, Mrs. Griffiths and Mrs. Wyatt.-Fronds tufted, 2 or 3 inches high, half a line in diameter at base, much but very irregularly branched, the branches cloven into many segments, which gradually taper to a fine point. The colour is olivaceous brown, becoming greenish grey and wholly without gloss in drying. The frustules are larger than in S. Smithii, longer and blunter, double, and rather densely set.

5. S. laciniatum; fronds robust, setaceous below, increasing in diameter upwards, very tender and gelatinous, elastic, cleft into very numerous, irregularly divided or simple branches, which taper to a fine point; frustules very minute, closely packed.

On rocks in the sea. On the Harbrick, in Torbay, Mrs. Griffiths. March.

-Fronds 2 or 3 inches high, "bright full brown," fading in the herbarium to olive-green," extremely tender and elastic, gelatinous, running together into a shapeless mass" (Griff. in litt.), subsimple and setaceous below, gradually widening upwards to 2 or 3 lines, and then cleft into very numerous, irregular, jagged branches. Frustules very minute and exceedingly nu. merous. This has something the habit of the last species, but the substance and frustules are very different.

Grev.

6. S. Smithii, Ag.; fronds robust, tufted, ultra-setaceous, gelatinous, elastic, firm, much but very irregularly branched; branches spreading, gradually attenuated, fastigiate; apices acute; frustules oblong, bright green, disposed in sub-distant rows, immersed in the colourless jelly of the frond. in Hook. l. c. p. 413; Crypt. Fl. t. 298; Wyatt, Alg. Danm. No. 151. Ulva foetida, E. Bot. t. 2101.-B. torquata; tufts globose, fronds very much branched, the branches and ramuli remarkably curled.

In the sea, on rocks and various Algæ; not uncommon. Salt marshes, Norfolk, Hooker. Bantry Bay, Miss Hutchins. Appin, Capt. Carmichael. Coast of Devonshire, Mrs. Griffiths and Miss Cutler. Antrim, Mr. D. Moore.-Fronds yellowish olive or greenish, tufted, 1 or 2 inches long, from the thickness of bristles to half a line in diameter at base, separating with elasticity in water, much branched in a subdichotomous manner; branches often palmate at the tips. Frustules large, binate, oblong or sublanceolate, disposed in subdistant lines. B. is remarkable for having all the branches curled and entangled; the frustules more distinctly in chains, and of a brighter colour than in the common state. It may perhaps prove to be a distinct species, but in the dry state it closely appreaches acknowledged states of S. Smithii. It was found at Torquay, by Mrs. Griffiths.

7. S. corymbosum, Ag.; "filaments laxly tufted, branched; branches divided towards the extremity in a penicillato-corymbose manner." Ag.-Grev. in Hook. l. c. p. 413.

66

On various small marine Algæ, corallines &c. Devonshire, Mr. Sconce. Tufts lax, about an inch in length, pale yellowish or reddish green. Filaments slender, irregularly branched, but generally at intervals in a fasciculate manner, the extremities corymbose." Grev. l. c.—I am unacquainted with this plant; and both Agardh and Greville are dubious respecting it. The latter remarks that it has an air of monstrosity. Perhaps it may be a variety of S. Smithii.

8. S. Wyattia; frond setaceous at base, capillary upwards, fastigiate, firmly cartilaginous, cleft to the base into several principal branches, each of which is again divided into others; branches very erect and straight, with acute axils, tapering to a fine point; frustules somewhat lanceolate, densely packed.

On rocks &c. in the sea. Torquay, Mrs. Wyatt. - Fronds setaceous at base, capillary upwards, an inch or more in height, fastigiate, forming globose tufts, firmly cartilaginous, opening with elasticity in fresh water after