172 ALG/E MELANOS PERMED. [ Desmareslia. 



thin, membranaceous, linear-lanceolate, entire frond. Hook. 

 Br. FL v. ii. p. 272. E. Bot. t. 1331. Turn. Hist. t. 164. 



Sea shore?, rare. Larne ; Mr. Templcton. Eantry bay ; Miss 

 Hutchins. Black rocks, Portstewart, County of Derry ; Mr. D. 

 Moore. Distinguished from the preceding by its thin membranaceous 

 substmce and lanceolate outline ; characters which are, 1 fear, not to 

 be depended on. 



Tribe IV. SPOROCHNOIDEiE. 



Plants marine, olivaceous or yellowish-green, much branched, the 

 branches mostly distichous, foliaceous, compressed, or filiform, inar- 

 ticulate, becoming flaccid on exposure to the air, "in some cases ac- 

 quiring, under such circumstances, a verdigris-green colour, and 

 then possessing the property of rapidly decomposing other delicate 

 Alga in contact with them. ,y Fronds generally bearing, at some 

 period of their growth, deciduous tufts of bright green filaments. 

 Fructification imperfectly known ; " composed of club-shaped, mo- 

 niliform, radiating filaments, either forming sessile warts, or ar- 

 ranged coiicentrically in little stalked, club-shaped bodies, terminated 

 by pencils of delicate fibres. Grev. — A small and natural family, 

 in many respects allied to the Laminariea?, from which tribe it is, 

 however, well distinguished bi/ the much branched frond, ivhich pro- 

 duces, in its young state, delicate tufts of fibres, and does not become 

 darker in drying or decay. 



8. Desmarestia. Lamour. Desmarestia. 



Frond plane or compressed, distichously branched; when young, 

 furnished with marginal deciduous tufts of fine green fila- 

 ments, the branches set with marginal spines. Grev. — Fruct. 

 unknown. — Name; in honour of A. G. Desmarest, a French 

 Naturalist. 



1. D. liyulata, Lamour. Ligulate Desmarestia. Frond much 

 branched, plane, Avith an obscure midrib, 3 — 4 times pinnated ; 

 pinnae and pinnulae linear-lanceolate, opposite, and (as well as 

 every division of the frond) attenuated at the base. Hook. Br. 

 FL v. ii. p. 273. E. Bot. 1. 1636. 



Not uncommon on any of our shores from the Giant's Causeway to 

 Bantry bay. Frond I — 6 feet long. 



2. D. aculeata, Lamour. Thorny Desmarestia. Frond ex- 

 cessively branched, branches alternate or irregular, very narrow, 

 linear, compressed, many times divided in a pinnate manner ; 

 margin of the pinnules set with alternate spines. Hook. Br. FL 

 v. ii. p. 273. E. Bot. f/2445. 



Sea-shores, common. The marginal spines ar« not produced till the 



