DISTRIBUTION OF MARINE A~LGM. 179 



that a number of the Antilles richest as regards Algae are 

 subject to irruptions of fresh and brackish water from the 

 Orinoco floods, a condition that would operate in the same 

 direction. "When I have finished the examination of 

 Indian Ocean Algae on which I am at present engaged, 

 check results may be expected that will answer this 

 speculation. The figures I have quoted to you with 

 those in the table speak for themselves. Out of three 

 diverse floras consisting of 259 species, 788 and 1132 

 respectively there are only 12 species in common. This 

 one fact surely answers the question plainly enough that 

 there is a subject of the distribution of Algse, and that 

 materials for its study exist ; and moreover it exhorts us 

 to undertake it. 



I now come to the last part of my subject and on it I 

 need not detain you long since the materials are scanty. 

 The distribution of Algae in time as evidenced by their 

 fossil remains is a branch of study which is indeed some- 

 what starved for lack of material. In the early rocks there 

 are many markings which have been dignified by imagina- 

 tive palaeontologists with such names as Fucites, Confer- 

 vites, Caulerpites, etc. But these have been shown by 

 Nathorst and others to be in most cases no other than 

 casual impressions of miscellaneous objects, trails of 

 creeping animals and the like. We have however certain 

 fossil remains such as Nematophycus described by Mr. 

 Carruthers, from the Erian of Canada ( = lower Devonian). 

 The minute structure of this Alga has been studied 

 microscopically and it is apparent that in these far off 

 times there flourished in the ocean, this gigantic sip- 

 honeous alga, resembling our Udotea or Avrainvillea in 

 structure but attaining a girth to be measured by feet — a 

 veritable marine tree. Besides this alga and a few 

 questionable forms such as Pachytheca, we have only 



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