ORTMANN : TERTIARY INVERTEBRATES. 313 



cific Ocean by way of a now submarine plateau (p. 433) "from Guinea 

 and North Australia, through the Fiji and Tonga Islands to Samoa, 

 spreading South to New Zealand and North to the Ellice, Gilbert, Mar- 

 shal, Caroline and Pelew Islands;" another plateau "extends from Chili 

 in a northwest direction to the Society Islands and Cook's Islands, in- 

 cluding Juan Fernandez, Easter Island, the Paumotus and the Marquesas 

 Islands." Thus these two plateaus closely approached each other, if they 

 were not actually connected. 



Shortly after Hutton's first publication, Gill (1875) presented another 

 somewhat similar view, but this was given in a very vague form. Con- 

 sidering the distribution of fishes, he divided the land masses in two large 

 sections, an Eogcea, comprising Africa, South America and Australia, and 

 a Gznogcea, comprising the rest of the present continental masses. He 

 does not introduce the Antarctic continent at all, and does not give any 

 details of the connection, simply intending this as a zoogeographical di- 

 vision. But the fact that he calls these two sections "areas of derivation 

 or gain from more or less distant geological epochs," and that he refers 

 to them again later (Science, 8 June, 1900), calling them "hemispheres," 

 makes it apparent that he understood his Eogaea as a large continental 

 mass. 



Thus we have to distinguish, practically, three different theories, aside 

 from Wallace's: (i) The Ruetimeyer-Hutton theory of the connection 

 through an Antarctic continent (1867, 1873); (2) Gill's Eogaea theory 

 (1875); (3) Hutton's theory of 1884, constructing a connection across 

 the mid-Pacific. In all these, the fundamental idea first expressed by 

 ' Hooker, that there must once have been a connection by land, serves as 

 a basis. 



Gill's theory has never been taken up by anybody else, while the two 

 other theories have been taken into consideration by subsequent writers. 

 Among them we should mention in the first line H. O. Forbes (1893). 

 He practically accepts the first and oldest theory of Ruetimeyer and 

 Hutton, in assuming the former existence of a larger Antarctic continent ; 

 but on the other hand, he goes far beyond Ruetimeyer's and Hutton's 

 ideas, in constructing this continent on a very large scale: his "Antarc- 

 tica," in its coast line, follows nearly what is now the 2000 fathom line, 

 and extends in broad stretches over Australia and New Zealand to the 

 Fiji Islands, to the Mascarene Islands and South Africa, and to South 



