202 SPENCER MOORE [September 



not the geuus have originated in Australia and passed thence via 

 Eastern Asia, where it is represented by several species, into North 

 America ? Only on the hypothesis that a genus must have arisen in 

 a larger area and that its presence in a smaller area must be due to 

 migration, which is a mere begging of the question, can the possibility 

 of a southern origin for Aster be denied. Mention may be made, too, 

 of Bassia, in Mueller's sense of the term, that is, as comprising Chenolea, 

 Selerolaena, Anisacantha, Threlkeldia, and part of Kochia as understood 

 by Bentham. Of these Selerolaena, Anisacantha, and Threlkeldia are 

 endemic in Australia, and the two species of Kochia, referred to Bassia by 

 Mueller, are also endemic there, Chenolea alone being extra-Australian 

 with nearly one-third of its species restricted to the island-continent. 

 Yet Bassia is held by Professor Tate to be a genus exotic to Australia ! 

 So, too, Kochia proper has 19 Australian species, all endemic, leaving 

 only 13 to be shared between South Europe, temperate Asia, North 

 and South Africa, India, and North-West America ; and when wo 

 remember that several peculiar genera allied to Kochia are exclusively 

 Australian, is there anything extravagant in the opinion that proba- 

 bilities point to this genus as having originated in Australia ? And 

 what shall we say of A triplex, of which many species are Australian, 

 and some of them extraordinarily abundant in individuals ? The 

 evidence for a southern orio;iu of such oenera as Ranunculus and 

 Clematis, Myosurus and Samolus is not so strong ; but when we come 

 to aquatics, such as Callitriche and Cercdophyllum and Potaniogcton, all 

 very extensively distributed, I do not see upon what grounds the 

 possibility of a southern origin for some of them can be scouted, and it 

 must not be forgotten that Myriophyllum belongs to an order reaching 

 its maximum of species in Australia. Then take the Grasses, an order 

 very abundant in both hemispheres. Why may not such genera as 

 Deyeuxia, Hierochloa, Stii^a, and Eragrostis, to mention a few only, have 

 originated in some southern land or lands, and migrated thence to their 

 present homes in the north ? 



These are merely a few cases mentioned by way of example : by 

 no means do they exhaust the list of genera for the southern origin of 

 which there is at least some probability. But it may be objected that 

 most of the genera cited above are not found in antarctic lands, and 

 how, it will be asked, is their absence explained if they had a southern 

 origin ? I reply that, for all we know to the contrary, antarctic lands 

 may, at some former time, have supported many supposed northern 

 genera now not found there. This traverses Mr. Darwin's opinion 

 when he says : 1 " I am inclined to look in the southern as in the 

 northern hemisphere to a former and warmer period, before the com- 

 mencement of the last glacial period, when the antarctic lands, now 

 covered with ice, supported a highly peculiar and isolated flora." But 

 with all deference to Mr. Darwin, why should the pre-glacial antarctic 



1 " Origin of Species," 6th ed. p. 341. 



