ORTMANN : TERTIARY INVERTEBRATES. 3 1 I 
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 with 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). 
