66 Marine Floras of the Warm Atlantic, 







region, though I have included a few forms from the Andaman Islands and 

 Mergui. The Cape of Good Hope region has already been indirectly 

 described, and, as has been said, extends for the reasons given slightly into 

 the tropics on the west coast, and recedes slightly from that boundary on 

 the east coast. 



The accompanying table speaks for itself so far as the results of the 

 comparison go, but a few remarks on what I take to be the meaning of 

 the figures may be thought not too venturesome. If we look first at the 

 last line of the table where the aggregates are set forth, it will be seen that 

 the warm Atlantic has the largest recorded flora, viz., 859 species in 162 

 genera. I may explain that, out of this total, no less than 788 species in 

 150 genera occur in the West India region, and that the rest of the warm 

 Atlantic furnishes only 71 species in 12 genera not occurring in the West 

 Indies out of a much smaller total flora. Allowing for the undoubted 

 fact that a large number of West Indian species are bad species, there 

 still remains a large balance in its favour. It has been better examined 

 than any other part of the warm Atlantic, but still we may attribute 

 this preponderance mostly to the favourable natural conditions, princi- 

 pally the coral formation of large portions of its island shores. On 

 the coast of Africa there is not only no coral, but league after league 

 of muddy shore, making a marine desert so far as Algae are concerned. 

 The Indian Ocean comes next, with 514 species in 139 genera. It 

 possesses an enormous coast line, to a considerable extent favourable 

 to the growth of Algae (though including long desert stretches) ; but 

 the bulk of the records are from Ceylon, Mauritius, and the Red Sea, 

 while a very large proportion of the region is unexamined. As in 







the West Indies, there is also here a considerable proportion of bad 

 species, principally Sargassa, from the Red Sea. From the Cape we 

 have 429 species in 141 genera. This remarkable total, from so short 

 a coast line, is obtained from Miss Barton's list in the Journal of 

 Botany, 1893. The flora previously recorded in books amounted only 

 t to 242 species in 99 genera, and this addition to its flora has resulted 

 from her examination of the British Museum Herbarium, and her naming 

 of the admirable collection made by Mr. Boodle, and also those made by 

 Mr. Scott Elliot and Mr. Tyson. The most noteworthy observation on 

 these aggregates is the proportion of species to genera. In the warm 

 Atlantic the genus averages well over 5 species ; in the Indian Ocean the 

 proportion is nearer 4 than 3 species to the genus ; while at the Cape it is 

 almost exactly 3. This is instructive when we remember, as I have 

 elsewhere pointed out,* that while the Arctic Algae average slightly more 



* Trans. Biol. Soc. Liverpool, vol. v., p. 177. 



