ZOOLOGY OF SCILLY. 229 



Tenby. Gemmaceas abound ; Daisies are frequent ; the 

 Dianthus is to be had ; also the Orange-disked ; and two 

 species, probably yet undescribed — of which more anon. 



To learn the geographical position of Scilly — above all, to 

 get a glance at the coast — you would imagine it to be a 

 wonderful place for marine zoology. The first obstacle lies 

 in the nature of the rock. Granite, indeed, as mere granite, 

 is almost as bad as chalk cliffs, which let no ingenuous 

 reader waste his holiday upon. The weeds are loth to grow 

 there ; and where no weeds grow, no herbivorous animals 

 will congregate for pasture ; consequently no carnivorous 

 animals will be there to pasture on them. The large amount 

 of silica in granite resists the decomposing action of winds 

 and waves, and of course still more energetically resists the 

 animals, who require, among other things, lime for their 

 shells. Drear and barren is many a hopeful-looking reef 

 here : and barren they would all be, were it not for the com- 

 pensating conditions of climate and tidal current. Scilly is 

 a little to the west of the sixth degree of western longitude, 

 and exactly in the fiftieth degree of northern latitude ; 

 consequently it is the most southern part of the United 

 Kingdom, if we exclude the Channel Islands. The mean 

 temperature in summer is 58°, and in winter 45°. The pre- 

 valent wind is south-west, or west-south-west. As a conse- 

 quence of this equable temperature, there are numerous 

 plants growing in the open air at Tresco, in the garden of Mr 

 Smith, the lord of the isles, which at Kew are to be seen 

 only in the hothouses. The aloes are magnificent : and rare 

 plants from California and New Zealand flouiish in profusion. 



