88 James Small on 



was well-advanced and mountain ranges were beginning to appear 

 in Asia and around the Mediterranean end of the Great Central 

 ►Sea. The Yablonoi, Altai and Thian Shan ranges and the 

 mountains of Afghanistan, Persia ;ind Asia Minor formed one 

 l)ath stretching from close to the northern end of the Rockies to 

 the Mediterranean region. While the Yablonoi, Khin gan, Sin- 

 Ling and Himalayan ranges formed another similar path through 

 China and Northern India to Asia Minor. Spurs from the latter 

 path led through the Malay Peninsula and Sumatra to Australia, 

 and also via the Philippines and New Guinea to the island 

 continent. 



Our wandering groundsel, showing its original liking for the 

 ' high " road, took both the main Asiatic ])aths, after coming 

 north along the Rockies and crossing the Alaska-Siberian bridge. 

 The wide, wet or frozen plains in the north were not congenial 

 and these far-stretching paths were not colonized to any great 

 extent, but the routes taken can still be traced by certain species. 

 Senecio altaicus, for example, occurs along the first path from 

 Siberia to Turkestan ; S. Ligularia occurs along the second path. 



The Mediterranean region, the next halting place, formed at 

 this time the eastern end of the Great Central Sea ANhich, by 

 gradual draining and drying up in succeeding ages, formed at one 

 end the semi-desert regions around Mesopotamia and Northern 

 Africa, and at the other end the similarly arid Mexican plains. 

 On reaching the warm woodlands, which at the end of the Eocene 

 covered the many eastern islands of this primeval sea, our 

 changeful groundsel in part again lost its pappus and by a 

 few other slight changes developed the corn marigold type 

 {Chryfiantkemum and its allies chamomile and yaiTO'v). Other 

 colonies of groundsel in the same region about the same time 

 developed by mutation a split down the back of the corolla, 

 which with some sligiit accompanying changes gave rise to the 

 lettuce and dandelion types. 



The conditions in this early Mediterranean zone were so 



