220 /'.'. ('. Andrew— The Geological History of t It* 



Sophora tetraptera, and Euphrasia aiilarctica, are amongst the 

 most noted in this connection. The struthious birds, as the 

 Rhea (S. America), the Ostrich (Africa and Asia), the Casso- 

 wary (North Australia), the Emu (Australia), the Moa (New 

 Zealand), and the Epyornis (Madagascar), are also cited as 

 evidence of former land connections between these regions. 

 Placostylus, among land shells, the earth-worms, the reptiles, 

 the marsupials, and other animals, are also cited as proof of 

 former land connections. 



It has been found difficult to discuss this most interesting 

 and complex problem with justice from the point of view of 

 the distribution of the animals, nevertheless it is just from the 

 animal distribution that the strongest case is said to have been 

 deduced for a former direct land connection between the vari- 

 ous areas under consideration. The construction of the hypo- 

 thetical continent Antarctica reaching arms of land to the 

 southern land masses of South America, South Africa, Aus- 

 tralia and New Zealand, and acting as a developing ground 

 for the life forms common to the areas under consideration, 

 is undoubtedly a most suggestive conception, and one which 

 especially in the form in which Iledley has stated it, appears 

 to be quite convincing from so many points of view. On the 

 other hand it would be advisable to indicate some of the dif- 

 ficulties in the way of accepting this idea which have been 

 suggested to the writer by a study of geology and botany. 



As a preparatory step, however, it might be advisable to dis- 

 pose of some of the general objections raised against this doc- 

 trine, which has been so suggestive and so full of promise to the 

 investigator. It is considered by certain biologists that the 

 plants and animals said to be common to South America, South- 

 eastern Australia, South Africa, and New Zealand, need no 

 direct land connections to explain their peculiar distribution 

 but that they are to be explained rather as similar biological 

 responses to similar environments. That is to say, the mar- 

 supials, the struthious birds, the pine trees, the beech trees, 

 and the other forms common to these regions arose indepen- 

 dently in each country as a response to a similar geographical 

 environment. 



Let us, in this connection, consider the case of the families, 

 genera, and species, identical in South America, Australia, and 

 New Zealand. The number of families of flowering plants is 

 about 250, nevertheless the possible number, probably, is legion. 

 Let us assume, however, that 250 is the limiting number. The 

 possible number of genera in a family is immense, as is at 



