(6) 



beset, especially upwards, with short spine-like ramuli, which extend 

 over the receptacles. Air-vessels scattered among the branches, single 

 or two or three together, often subtending the axils, small and incon- 

 spicuous, elliptical. Substance coriaceous, very hard and woody in the 

 older parts, and not adhering to paper. Receptacles linear lanceolate, 

 unequally tubercular. Colour, a rather transparent olive green, almost 

 black when dry. 



This curious species is readily known from all the other British species 

 by the curiously swollen bases of the branches, and more slender habit ; 

 still, however, exhibiting the rigid, bushy, shrub-like habit of the genus. 

 The whole genus might well be denominated the sea-shrubs of OTir shores ; 

 they afford a striking and peculiar character to the marine vegetation 

 in the warmer regions of the temperate zone, where they are chiefly 

 found. They become rarer as we proceed northwards, most of the 

 species reaching their northern limit before arriving at the British Isles, 

 on the southern shores of which only they can be said to be frequent, 

 scarcely any of them being found on our northern shores, where their 

 place is supplied by the Fuci, which are rare in the south, and gradually 

 increase in abundance as the Cystoseiroe diminish, until in the northern 

 part of the temperate zone they entu*ely occupy their place. 



The various species of Cystoseira, like their analogues on land, form 

 a safe retreat and shelter for the vast myriads of marine animals that 

 swarm in every pool during the su.mmer months. Both MoUuscs, 

 Zoophytes, and Crustaceans seem to vie with each other in rendering 

 them replete with life ; a single plant of Cystoseira would be an interest- 

 ing subject of study almost for a life-time, while the details of habits 

 and instincts of its varied inhabitants would supply ample materials to 

 fill a volume. 



EXPLANATION OF PLATE CXXXII. 



Fig. 1. — Cystoseira granulata, natural size. 

 2. — Receptacle. 

 3. — Section of same. 

 4. — Semisection of conceptacle. 

 5. — Spores. All magnified. 



