12 SYNOPSIS OF BRITISH BBAWBED8. 



clearly no claims to be admitted to the British Flora, but 

 having alreadv been introduced into other works, I figure 

 it, though obliged to take my drawing from a foreign spe- 

 cimen. The branch shown in the figure is pari of a spe- 

 cimen picked up at sea. in tin' great floating bank of Gulf- 

 weed n\ hich extends at the wo>tw ard of the Azores from the 

 twentieth to the thirty-sixth degree of north latitude. &W- 

 gasstun bacciferum is found in ridges from ten to twenty 

 yards wide, and of indefinite length, stretching across the 

 sea. In this situation it continues to grow luxuriantly, and 

 appears to multiply itself by offsets, at first accidentally 

 broken off, and immediately establishing themselves as in- 

 dependent plants. A great variety of marine animals, from 

 Crustacea downwards, inhabit its branches, but I have 

 observed no parasitical Algse on any of the specimens 

 picked up. The list of animal species would afford subject 

 for a small volume, but very few of them are of a strictly 

 parasitical nature. 



II. HALIDRYS. 



3. siliquosa (The podded Halidrys) ; branches linear, very 



narrow ; air-vessels compressed, linear-lanceolate, >lightly 



constricted at the septa, mucronate, Lyngb. Hyd. D.p.37. 



(Atlas, PI. I. Fig. 3.) 



Cystoseira siliquosa, Ag. Fucus siliquosus, Linn. F. siliculosus, 



Stack. 

 Sab. Common on the shores of the British Islands. On rocks 

 and stones in the sea, at and below half- tide level. Perennial. 

 Winter and spring. 

 One of the handsomest of British Fucacece, and common 

 on all our shores. It is subject to little variation, except in 

 size. When growing in shallow water, or in tide-pools near 

 high- water mark, it becomes stunted in its habits, having 

 the branches more closely set, and bushy, and every part 

 proportionally smaller and narrower. This state consti- 

 tutes the var. /3 of authors. The genus Halidrys, founded 

 by Lyngbye, is well distinguished from all other Fucacecr by 

 the curious structure of its air-vessels. These compound 

 air-vessels are confined to the present individual, and to the 

 beautiful Fucus osmundacens of Turner, a native of the 

 west coast of Xorth America. In this latter species the 

 structure is slightly different, and the vesicles are much con- 

 stricted at the joints, like strings of beads. r ihj whole 



