ORTMANN : TERTIARY INVERTEBRATES. 311 



given by Hedley (1895) who has formulated his own views in the follow- 

 ing words (1. c., p. 6) : "... during the Mesozoic or older Tertiary, a 

 strip of land witli a mild climate extended across the South Pole from Tas- 

 mania to Tierra del Fuego, and . . . Tertiary New Zealand then reached 

 sufficiently near to this Antarctic land, without joining it, to receive by flight 

 or drift many plants and animals!' 



This theory, which has been worked out more especially in its bearing 

 upon the Australian and Pacific faunas in a later paper by the same 

 author (Hedley, 1899), differs in important points from all theories 

 hitherto advanced, as it demands only a minimum of land extension, and 

 further, as he states expressly (p. 7) that this Antarctic continent ("Ant- 

 arctica") was probably "an unstable area, at one time dissolving into an 

 archipelago, at another resolving itself into a continent." He admits 

 further the existence of certain facts that suggest a former connection of 

 South Africa also with Antarctica. 



The facts leading to this and the older theories were observed long 

 ago, and consist of a marked similarity in the animal and plant life of 

 the respective continents, a similarity which is also recognizable, as we 

 have seen above, among the fossil marine animals. With the exception 

 of the theory of Wallace (1876, pp. 287 and 461), who believes that the 

 common elements of the southern faunas have been derived from a gen- 

 erally distributed stock, which was pushed by the competition of other 

 animals into the southern ends of the continental masses, where it alone 

 survived, all explanations of this zoogeographical fact have started from 

 the fundamental idea that there must formerly have existed a connection 

 between the respective parts by a land bridge, and opinions differ only as 

 to the location and probable extent of it. As to the time of its existence 

 there is a fairly complete unanimity among the writers on this subject, 

 provided that they have given any expression at all of their opinions on 

 this point; if they construct this bridge for any particular time, it is for 

 the end of the Secondary or the beginning of the Tertiary. Only Forbes 

 (1893) makes an exception by putting his Antarctica into the "Ice age." 



To my knowledge, 1 Hooker was the first to hold the opinion that, with 

 reference to plant life, there may have existed a connection of the differ- 

 ent parts of Antarctic and Subantarctic continents and islands by land. 



1 See Ortmann, "The Theories of the Origin of the Antarctic Faunas and Floras" (American 



Naturalist, v. 35. February, 1901). 



