MIOCENE ATLANTIS. 35 



of the Sargasso Sea or Gulf weed in the middle of the Atlantic ; and, as the claim founded on the 

 existence of that weed applies not only to this case, but may have to be considered in other 

 parts of the world, it may be desirable to state once for all in some detail the grounds on which 

 his hypothesis is founded. They are contained in the following note by Edward Forbes in his 

 paper on " The Geological Relations of the Existing Fauna and Flora of the British Isles :" — 



" The following extract from the writings of one of the first of li\Tiig Algologists (Prof. Harvej-) 

 will show that there are botanical grounds for my speculation respecting the Gulf weed. ' Authors 

 wlio have written on this Fxrus, have much disputed both regarding its origin, and whether 

 it continues to grow whilst floating about. Nothing at all bearing on the former question has 

 yet been discovered ; for, though species of Sargassiim abound along the shores of tropical coun- 

 tries, none exactly corresponds with S. bacciferum. That the aiwesfors of the present bank have 

 originally migrated from some fixed station is probable ; but fui-thcr than probability we can say 

 nothing. That it continues to flourish in its present situation is most certain. Whoever has 

 picked it up at sea and examined it vrith. any common attention, must have perceived not only 

 that the plants were in vigorous Kfe, but that new fronds were continually pushing out from the 

 old, the limit being most clearly defined by the colour, which in the old frond is foxy-brown ; in the 

 young shoots, pale, transparent olive. But how is it propagated, for it never produces fructification ? 

 It appears to me that it is by breakage. The old frond, which is exceedingly brittle, is broken 

 by accident, and the branches continuing to Uve, push out young shoots from all sides. Manj- minute 

 pieces that I have examined were as vigorous as those of larger size, but they were certainly not 

 seedlings, and appeared to me to be broken branches, all having a piece of old frond from which the 

 young shoots sprung. As the plant increases in size it takes something of a globular figure, from the 

 branches issuing in all directions as from a centre. On our own shores we have two species analogous 

 to S. bacciferum in their mode of growth, namely, Fucus Mackayi and the variety B. sub-ecostata of 

 Fiwus vesicnlosus (F. Balticus, A'g.) Neither of these has ever yet been found attached, though they 

 often occur in immense strata ; the one on the muddy sea-shore, the other in salt marshes, in which 

 situations respectively thej^ continue to grow and flourish ; and it is remarkable that neither has ever 

 3'et been found in fructification, in which respect also they strikingly coincide with S. bacciferum. 

 And if it be hereafter shown that F. Mackai/i is merely F. nodosus altered by growing under peculiar 

 circumstances, may it not be inferred that Sargassum bacciferum, ■which difiers about as much from 

 Sargassum rulgare as Fucus Mackayi does from Fucus nodosus, is merely a pelagic variety of that 

 variable plant ? ' — Harvey, Manual of the British Alga- (1841.) Introduction, pp. 16, 17. 



" My friend and colleague. Dr. Joseph Hooker, who has had great opportunities of studying the 

 Gidf weed, believes with Dr. Harvey, that the Sargassum bacciferum is an abnormal condition of 

 S. vulgare. Now as the latter is essentially a coast-line plant, growing on rocks with a very limited 

 vertical range, I propose to account for its abnormal condition as Sargassum bacciferum in the Gulf 

 weed bank, on the supposition of the subm,ergence of the ancient line of coast on which it originated."* 



The idea here may either be, that the weed has spread from the ancient submerged line of coast 

 over the whole of the rest of its bounds, or that the limits or outer margin of the Sargassum mark 

 the ancient original coast-line, and that the whole of the space within these limits has been filled 

 up with Sargassum by its having by successive subsidences aU passed through the phase of coast-line. 



* Ed. Forbes, on the Geological Relations of the exist- the Geological Survey of Great Eritain and of the Museum 

 ing Fauna and Flora of the British Isles in "Memoirs of of Economic Geology." London, 184G. Vol. i. ji. 349. 



