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FLORA OF MARIOX ISLAND. 485 



At about 1400 feet elevation the water in a shallow pool ex- 

 posed to the sun was found to have a temperature of 65° F., the 

 temperature of the air in the shade being 44°. At 900 feet a 

 similar pool, but one which had a small stream of colder water 

 running into it from the cliff, had a temperature of 55°, the air 

 here being at 45°. The thermometer here, when plunged into 

 the midst of a rounded mass of Azorella, rose to 50°. It is evi- 

 dent that these mounds retain and store up a considerable quantity 

 of the sun's heat ; and this fact probably yields an explanation 

 of their peculiar form, w r hich is that of so many otherwise widely 

 different Antarctic plants. 



The island being of such considerable area, and so short a time 

 having been available for the examination of its flora, no conclusions 

 can be drawn from the absence of certain plants, such as Lyallia, 

 which might have been expected to occur there, since they occur in 

 Kerguelen's Land associated with nearly all those found. Although 

 the few plants on such islands as these are, as a rule, widely 

 spread, yet some appear to be local and somewhat scarce, as, for ex- 

 ample, the Aspidium and Asplenium, which were only found at the 

 last moment, the latter almost by accident. It is thus highly 

 probable that several plants have been overlooked, and amongst 

 them probably Lyallia. The nine flowering plants collected are 

 probably all identical with the species growing in Kerguelen's 

 Land ; and the same is the case with the club-mosses. The 

 ferns form the most remarkable feature in the flora, since there 

 are here five species, whilst only one occurs in Kerguelen's Land*. 

 The occurrence of Pringlea on the island, as also on the Crozets 

 and Kerguelen's Land, points to an ancient land- connexion between 

 these islands, which the antiquity and extent of denudation of the 

 lavas would seem to bear out. It is difficult to see how such 

 seeds as those of Pringlea could have been transported from 

 one island to another by birds ; and the seeds seem to be remark- 

 ably perishable ; besides, the distinctness of the genus points to 

 a former wide extent of land on which its progenitors became de- 

 veloped. The existence of fossil tree-trunks in the Crozets and 

 Kerguelen's Land points to similar conditions. 



Sixteen vascular plants were found in the island of Marion ; 

 Kerguelen's Land has nineteen — but amongst these only one fern 



Since these notes were written, in 187*3, other forms have been found in 

 Kerguelen's Land bv the " Transit-of- Venus " Expeditions. 



