CATENELLA. CRUORIA. 151 



immersed in the substance of the frond beneath the periphery. The frond 

 of this species is occasionally eaten by the poor, either raw or cooked in 

 the frying-pan. 



XV. CATENELLA. Grev. [Plate 20, B.] 



Frond dull purple, membranaceous, filiform, constricted 

 at intervals ; its axis composed of a lax net-work of anasto- 

 mosing, longitudinal filaments. Fructification : 1, spherical 

 masses of spores (favellidia) contained in external, capsular 

 bodies ; 2, oblong, transversely parted tetraspores, immersed 

 among the filaments of the periphery. Name a diminutive of 

 catena, a chain. 



1. C. Opuntia, Good, and Woodw. Grev. Alg. Brit. p. 

 166, t. 17; Hook. Br. Fl.\\. p. 309; Wyatt, Alg. Danm. 

 No. 126 ; Harv. Phyc. Brit. t. Ixxxviii. Rivularia Opuntia, 

 E. Bot. t. 1868. 



Marine rocks near high-water mark, not uncommon. Fronds densely 

 matted together, half an inch to an inch high, rising from a mass of creep- 

 ing fibres; branches erect, simple, or slightly branched in an irregular man- 

 ner, contracted at intervals as if jointed ; the internodes or spaces between 

 the contractions narrow at base, gradually swelling upwards. Colour a 

 dull, dark purple. Substance membranaceous, tender and soft, more or 

 less full of moisture, imperfectly adhering to paper. 



XVI. CRUORIA. Fries. [Plate 20, C.] 



Frond gelatinoso-coriaceous, forming a skin on the surface 

 of rocks, composed of vertical, tufted, simple, articulated fi- 

 laments, set in a firmly gelatinous matrix; one of the joints 

 of each filament larger than the rest. Fructification : tetra- 

 spores lying at the base of the filaments. Name, from cruor, 

 blood; because the plant looks like a blood-stain on the 

 rock. 



1. G.pellita, Lyngb. Harv. Pliyc. Brit. t. cxvii. Chce- 

 tophora pellita, Lyngb. Hyd. Dan. p. 193, t. 66; Harv. in 

 Hook. Br. Fl. ii. p. 390 ; Harv. Man. 1st ed. p. 123. 



On smooth exposed rocks and stones, between tide-marks. Perennial. 

 Fruiting in February, Carm. Common on most of the rocky shores of 

 Britain. Fronds forming smooth, glossy patches of 2 3 inches in dia- 

 meter, on the surface of smooth rocks, at first circular, afterwards irregu- 

 larly shaped, between gelatinous and leathery, wholly composed of vertical, 

 coloured filaments set in a colourless jelly. Filaments tufted, perfectly 

 simple, dull purple. 



