T46 PRINCE EDWARD ISLANDS. 



appeared from this point to be continued on for about 300 feet 

 more, becoming scantier and scantier. The absolute limit of 

 vegetation may probably be placed at about 2,000 feet. The 

 part explored was somewhat sheltered. A red cone of scori?e 

 more exposed was quite bare of green from about 1,000 feet 

 elevation upwards. 



At about 1,400 feet elevation, the water in a shallow pool 

 exposed 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 evident that these mounds retain and store up a 

 considerable quantity of the sun's heat ; and this fact probably 

 yields a partial explanation of their peculiar form, which is that 

 of so many otherwise widely different Antarctic plants, and of 

 some New Zealand Alpine plants {Raoulia, Hastia). No 

 doubt one of the chief causes of assumption of this form is the 

 power of resistance to the wind thus gained. 



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 LvaHia, 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 example, the Aspidium, 

 which was only found at the last moment, under the banks of 

 one of the streams. It is thus highly probable that several 

 plants have been overlooked, and amongst them possibly 

 Lyallia. The nine flowering plants collected in the island 

 are all identical with the species growing in Kerguelen's Land ; 

 and the same is the case with the Club-mosses. Of the ferns, 

 two occur in Kerguelen's Land, which has also two others not 

 occurring here. 



Fifteen vascular plants in all were found in the Island of 

 Marion. 



Mr. Darwin suggests that Kerguelen's Land has been mainly 

 stocked by seeds brought with ice and stones on icebergs.* 

 The occurrence of Pringlea on Marion Island, as also on the 

 Crozets and Kerguelen's Land, probably points, however, to 

 an ancient land connection 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 



* " Origin of Species," 6th Edition, p. 354. 



