Bibliographical Notices, 129 



instrumental in calling forth one of the first botanists of the day to 

 their further illustration. It is a curious but happy coincidence, that 

 two botanists, Decaisne and Agardh, deeply imbued with philosophic 

 views, though occasionally differing on important points, should al- 

 most at the same time have published an account of the Algse of two 

 neighbouring seas approaching so near to each other in point of di- 

 stance, though differing so much in many essential points, as the 

 Red Sea and the Mediterranean. 



The following passage from Agardh's preface gives a very interest- 

 ing general view of the nature of the marine vegetation of the Me- 

 diterranean. 



The vegetation of the Mediterranean compared with that of neigh- 

 bouring seas presents a somewhat peculiar aspect. Species which 

 inhabit the Red Sea scarcely occur in the Mediterranean, w r ith the 

 exception of certain cosmopolites which are almost universally dis- 

 tributed ; the genera which are most characteristic of the former and 

 most numerous in species, Sargassum and Caulerpa, are represented 

 in the Mediterranean by very few, and those distinct species. Nor 

 is the difference much less between the vegetation of the Mediter- 

 ranean and Atlantic ; the genus Fucus, which abounds in the At- 

 lantic, is altogether wanting in the Mediterranean, or represented by 

 mere floating specimens, which assume however a peculiar form in 

 the Adriatic ; many species of Floridece {Chondrus crispus and Ch. 

 mamillosus, Rhodomenia laciniata, Rh.palmetta, Rh.ciliata, Delesseria 

 sanguinea, D. sinuosa, D. alata, &c.) of the tribes Sphcerococcoidece 

 and Delesserice, which abound in more open seas, do not adorn the 

 rocks of the Mediterranean ; Callithamnia and Ceramia become scarce. 

 On the contrary, the genera Bryopsis, Valonia, Griffithsia and Poly- 

 siphonia are more numerous in the Mediterranean, and the vegeta- 

 tion of rocks exposed to the sun (embracing very many Zoospermece, 

 Laurencice, &c, which are more generally cosmopolites) boasts of 

 perhaps an equal number in either sea. The degree of exposure to 

 light, and the greater or less motion of the waves, are important mo- 

 menta in the distribution of species. 



In the larger and more tranquil and sunny bays, especially those 

 which are shallow and sandy, Zoospermece principally occur, which 

 are generally adorned with a brighter green in consequence of the 

 greater intensity of the light. Rivularice, Lyngbyce and many Con- 

 ferva flourish on the stones scattered about high- water mark ; Bry- 

 opsis myura, Anadyomene, Dasycladus and many Laurencice grow on 

 the larger rocks. On stones which are more submerged and conse- 

 quently less exposed to light, are found Cystoseira barbata, C. crU 

 nita, C. selaginoides, &c, Sargassa, Codium Bursa, Padina pavonia, 

 Liagorce, &c. 



In deep and very tranquil bays, which are less exposed to light, 

 we may expect Siphonece and Dictyotece ; most of the species of Bry- 

 opsis, Valonia intricata, Codium tomentosum, Asperococcus bullosus, 

 Stilophorce, Striaria, Cutleria, Zonarice, Halyseris and Diclyota adorn 

 the stones and rocks with many species. The Floridece love the open 

 sea, choosing however rocks concealed from light and not exposed 

 Ann. fy Mag. N. Hist. Vol.x. K 



