A plant so nearly related to the common L. muralis, of Britain, as to require no detailed description.
Plate CXCIII. Fig. II. — 1, plant of the natural size ; 2, thread, highly magnified ; 3, portion of ditto : — still more highly magnified.
3. Lyngbya subarticulata, Hook. fil. et Harv. ; filis tenuissimis laxe implexis vix tortis hie illic obscure subarticulatis, sporidiis disciformibus diametro variis filum vix sequantibus ad articulos spurios fili solutis.
Hab. Christmas Harbour, Kerguelen's Land ; creeping amongst Viva &c, on wet rocks near the sea.
Fila cylindracea, sub 10 ' 00 unc. lata, pellucida, obscure articulata, articulis diametro ter longioribus, intus cum axi e sporidiorum disciformium composito aucti. Sporidia leete viridia, opaca, ter quaterve latiora quam longa.
A very different species from either of the two former. Each filament is a transparent tube, very obscurely incrassated, as if jointed here and there, and containing an axis of sporidia about half its own diameter. The sporidia are discoid, of various breadth and length, but always much broader than long, of a bright green colour, and interrupted opposite the spurious articulation of the fdament.
51. MICROCOLEUS, Besmaz.
1. Microcoleus repens, Harvey; Manual, p. 168. Oscillatoria repens, Agardh Syst. p. 61. O. chthonoplastes /3, Harvey in Hook. Brit. Fl. vol. ii. p. 373.
Hab. Cockburn Island, Graham's Land; (Lat. 64° S. Long. 57° W.) on the ground.
Our specimens are very poor, as might be expected from the native place being on the limits of vegetation in that quarter of the globe which the plant inhabits.
52. ULVA, L.
1. Ulva Lactuca, Linn; Grev. Scot. Crypt. Flor. t. 313.
Hab. Hermite Island, Cape Horn ; sparingly.
2. Ulva latissima, Linn.; Engl. Bot. 1. 1551.
Hab. Hermite Island, Cape Horn ; Falkland Islands and Kerguelen's Land ; very abundant.
There is probably no shore between that of Iceland and Cape Horn, that does not produce abundantly this species of Alga.
3. Ulva rigida, Agardh, ? Syst. Alg. p. 189.
Hab. Port "William, Falkland Islands; common.
Our specimens appear to be only a young dark-coloured variety of the former. The species is also a native of Brazil, and the west coast of South America.
4. Ulva Linza. Linn. ; Harv. Phyc. Brit. t. xxxix.
Hab. Falkland Islands and Hermite Island, Cape Horn ; abundant.
An abundant plant in the Atlantic and Mediterranean shores of Europe ; it has also been collected in New Zealand,
5. Ulva crista, Lightf. ; Harvey, Manual, p. 171.
