Dasya.] ALGJE RHODOSPERME^E. 209 



15. P.fastigiata, Grev. Fastigiate Polysipkonia. Filaments 

 rigid, setaceous, equal, many times dichotomous, fastigiate; 

 axils patent ; articulations shorter than their diameter, multi- 

 striate. Harv. in Hook. Br. Fl. v. ii. p. 333. Cow/, polymor- 

 pha. Dillw. t. 44. E. Bot. t. 1764. 



Parasitic on Fucus nodosus and F. vesiculosus, very common. Dark 

 brown, rigid, forming round bushy tufts. 



ff f Stems riff id, cartilaginous ; ramuli flaccid^ delicate. 



16. P. elongata, Grev. Lobster-horn Polysiphonia. Stems 

 robust, cartilaginous, irregularly branched, beset, especially 

 toward the apex, with slender, broadly fasciculate ramuli, atte- 

 nuated at the base ; articulations about as long as broad, those 

 of the stem reticulated with veins. Harv. 1. c. Conf. elongata, 

 Dillw. t. 38. E. Bot. t. 2429. 



Sea-shores, common. The largest of our native species, with very 

 robust stems. It varies both in the ramification, and in the more or 

 less crowded ramuli (in some varieties they are entirely wanting) ; yet 

 the student will readily recognise it under all its appearances. The 

 stems are of a dull red colour ; the ramuli are brilliant crimson. 



17. P. byssoides, Grev. Byssoid Polysiphonia. Filaments 

 cartilaginous, alternately branched ; branches decomposito-pin- 

 nate, patent, crowded ; ramuli short, squarrose, capillary, inul- 

 tifid, single-tubed ; articulations of the stem 3 4 striate, 2 4 

 times as long as broad. Harv. in Hook. Br. Fl. v. ii. p. 334. 

 Conf. byssoides, Dillw. t. 58. E. Bot. t. 547. 



Bantry bay ; Miss Hutchins. Very common on our eastern and 

 rare on our western shores. A delicate species, fine red when quite 

 recent, but rapidly changing to a dull brown in fresh water, or on ex- 

 posure to the air. It is easily distinguished from all our native species 

 by its single-tubed ramuli : indeed this character, together with its 

 peculiar habit, would lead one to suspect that it belonged more pro- 

 perly to Dasya than Polysiphonia, but it does not produce the 

 stichidia peculiar to that genus. 



52. DASYA. Ag. Dasya. 



Frond filamentous; main filaments inarticulate, cartilaginous, 

 beset with articulated, penicellate or pinnate, single-tubed 

 ramuli. Fructification double : 1. coriaceo-acuminate cap- 

 sules, furnished with a terminal pore, and containing pear- 

 shaped seeds: 2. lanceolate receptacles ( stichidia )> contain- 

 ing granules set in transverse fascia. Name ; da?, hairy ; 

 in allusion to the slender ramuli. 



1. D. coccinea, Ag. Scarlet Dasya. Stems elongated, ro- 

 bust, irregularly branched ; branches bipinnate ; pinnulae fasci- 

 culato-multifid ; articulations of the ramuli as long as broad. 



2c 



