XXXviii INTRODUCTION. 



may be regarded as on a level in organization with Codium, 

 have as wide a range. Among the Rhodospermece and 

 MelanospermecB it is more rare to find species so indifferent 

 to climate or country, and which we may term cosmopolitan 

 or pelagic races ; but in the former we observe Plocamium 

 coccineum and Gelidium corneum common to the Atlantic 

 and Pacific, and even Indian oceans ; Rhodymenia pal- 

 mata found at the Falkland Islands and Tasmania; while 

 Ceramium rubrum and diaphanum are as widely scattered 

 as the UlvtB : and in the latter, Fucus luberculatus is found 

 from the shores of Connaught (perhaps its northern limit), 

 to the Cape of Good Hope ; F. vesiculosus as well on the 

 north-west coast of America as on the shores of Europe ; 

 and Desmarestia ligulata in the northern Atlantic and 

 Pacific oceans, as well as at the Cape of Good Hope and 

 Cape Horn ; while Sargassum bacciferum and vulgare are 

 proverbial wanderers, and some species of Ectocarpus 

 usually accompany the Ceramia and Vivas. These excep- 

 tions sink into insignificance, however, when we consider 

 the whole series of Algas, the vast majority of which are 

 strictly limited in dispersion ; and in the following obser- 

 vations Lamouroux is substantially correct. " I have ob- 

 served," says he, " that the Atlantic basin from the polar 

 circle to the 40 of north latitude, offers a peculiar vegeta- 

 tion ; that the same is true of the West Indian sea, com- 

 prising the Gulf of Mexico ; of the east coast of South 

 America; of the Indian ocean and its gulfs; and of the 

 seas of New Holland. The Mediterranean * has a system 



* This observation is true in the main ; but many Algae which were 

 supposed to be peculiar to the Mediterranean when Lamouroux wrote 

 his essay have since been detected in widely distant seas. Some have 

 been found on the shores of Britain ; several on the east coast of North 

 America, from New York to Florida ; and others sent from the still more 

 distant shoves of New Holland. 



