84 SYNOPSIS OF BBITISn SEAWEEDS. 



fcufle, sometimes cruciform, Lamour. Ess. p. 12. (\\ 

 PL XXIX Fig. L32.) 

 Laurencia intricate, Lamx. L. ^elatinosa, Lamx. L.lutea, I 



L. cyanosperma, Lamx, Chondria obtusa, A<j. Fucos ob- 

 tusns, Hud*. PL Ang.p. 586. 

 Hah. Parasitical on the B ma Her Algee between tide-marks. An- 

 nual. Summer. 

 This species is as widely dispersed over the world as L. 

 pinnatifida, and though not quite so variable as that plant 

 in general appearance, nevertheless exhibits considerable 

 varieties. This is to be expected in a plant which grows 

 as well in subtropical as in temperate waters ; and which 

 even extends within the tropics. On our shores, except 

 in colour, it preserves most of the characters represented 

 in the Plate ; but Continental specimens are often much 

 taller in proportion to their breadth, till the pyramidal out- 

 line becomes almost as long, in proportion to its base, as 

 an obelisk. When growing in sunny pools the whole plant 

 often becomes pale yellow, preserving merely in the young- 

 est ramuli a rosy hue ; but in deeper water, and under the 

 shade of leafy Algae, all the branches are of a full red. 



138. dasyphylla (The thick-leaved Laurencia) ; frond cylin- 

 drical, filiform, decompound-pinnate or irregularly branched ; 

 branches erecto-patent ; ramuli short, club-shaped, obtuse, 

 transversely striate, very much attenuated at the base, Gr. 

 Alg. Br.p.112. t. 14./. 13-17. (Atlas, PL XXXII. Fig.144.) 

 Laurencia csespitosa, Lamour. Chondria dasyphylla, Ag. Grigar- 



tina dasyphylla, Lamour. Fucus dasyphyllus, Woodw. 

 Hab. On stones and shells in pools, near low-water mark, gene- 

 rally where the surface is covered with sand or mud. An- 

 nual. Summer. Frequent. 

 Laurencia dasyphylla belongs to a section of the genus 

 distinguished by having a jointed axis, composed of four 

 or five large cells surrounding a central cavity, exactly as 

 in Rytiphl&a : and as these cells are all of equal length, 

 their upper and lower extremities form transverse lines, 

 which, seen through the minute cells of the surface, have 

 the appearance of striae. In the present species these striae 

 are at very short intervals. They are much more apparent 

 in the younger parts of the frond, but the structure on 

 which they depend is equally obvious, on dissection, in all 

 parts. The geographical distribution of this species is very 

 extensive. I have received it from many distant quarters, 

 both of the Northern and Southern Hemispheres. 



