FORMER LAND CONNECTIONS. 123 



and Protopterus in Africa, and Lepidosiren in Brazil, while living 

 or recently extinct large birds of the Struthio type characterise the 

 above-mentioned countries, and in addition Madagascar and New 

 Zealand. These ancient lands have formed for such long-pedigreed 

 forms what Suess has aptly termed asylums. 



Recently new links have been obtained. Pkreatoicus is a 

 minute shrimp-like crustacean intermediate between the Isopoda 

 and the Amphipoda. It lives in tarns and, first found in Tasmania 

 and Victoria, was not so long since discovered on Table Mountain 

 and Sneeuw Kop in the Western Province. 



The Phreodrilidae are worms up to an inch in length inter- 

 mediate between the terrestrial and the aquatic Oligochaeta, and 

 are found in pools on mountain peaks in Australia, Tasmania, New 

 Zealand, Kerguelen Island, South Africa, Falkland Islands, and 

 Patagonia. They are descendants of an old cold climate stock, and 

 clearly could not have crossed the oceans. There is almost a 

 similar distribution in the case of the remarkable Peripatus. 



The Northern and Southern Floras of the Carboniferous 



Period. 



It is, however, when we come to consider the life of the past 

 and compare the geology of the regions concerned that the evidence 

 piles up in a rapid and most convincing manner. 



To do so it is necessary to go back to the Carboniferous epoch, 

 to the time when in the northern hemisphere the forming of coal- 

 seams was actively in progress. Such coals are believed to have 

 been accumulated on vast flats comparable in some respects with 

 the Great Dismal Swamp of Virginia, the climate being moist and 

 probably temperate. 



The vegetation at that period included many strange forms, 

 mostly vascular cryptogams, predominantly Equisetales, Lycopodia, 

 Pteridosperms and Ferns — a rather monotonous assemblage all the 

 same. 



This will be referred to as the "Northern Flora." 



In the southern hemisphere and in India, on the other hand, 

 the climatic conditions became such as to lead ultimately to the 

 development of extensive snow and ice caps at a number of separate 

 centres. Continued accumulation of snow caused huge ice-sheets to 

 spread outwards and move across the lower ground, just as in the 

 cases of Greenland and Antarctica at the present day. 



At the period of maximum glaciation no small proportion of 

 the southern hemisphere must have lain buried beneath a mantle 

 of ice thousands of feet in thickness, just as at a very much later 

 date was the case in the northern hemisphere during the Great 

 Ice Age; the details will be discussed shortly. 



At the same time, and according to some palaeobotanists as 

 a consequence of the general lowering of temperature, a flora made 

 its appearance quite distinct from that of the northern hemisphere, 

 known as the "Southern" or " Glossopteris Flora," from the name 

 of the tongue-shaped frond of its commonest form; this vegetation 

 gave rise to the coal-seams of Gondwanaland. 



11 



