1869.] HUNT — VOLCANOES AND EARTHQUAKES. 387 



tion of these species are especially great in conseo|uence of the 

 long continuous lines of railway and water communication be- 

 tween the seaboard and all sections of the interior. Many intro- 

 duced plants are thus of wide range. Capsella bursa pastorls, 

 Moench, Achillea miUefolium, L., Maruta cotida, D. C., Cy- 

 noglossum officinale, L., and Polygonum persicaria, L., for ex- 

 ample, extend from Lake Superior to the Lower St. Lawrence. 

 Others, again, are quite restricted in range. Leontodon autum- 

 nale, L., and Senebiera didyma, Pers., are limited to the sea- 

 ports, and S. coronopus, D. C, is only known from Gaspe ; Ve- 

 ronica chamcedrys has not been observed elsewhere than at Que- 

 bec ; Sisymbrimn sophia, L., is uncommon in the Province of 

 Quebec and quite unknown west of Prescott, and Flantago 

 media, L., has, as yet, only been observed at Toronto. 



Currents may play a more important part in the introduction 

 of exotic plants than is generally supposed. Our Canadian lake 

 coasts supply illustrations of this agency at work. Coral islands 

 are, it is well known, mantled with a vegetation largely resulting 

 from the seeds carried to their shores through the medium of 

 winds and currents. In the United Kingdom, the influence of 

 the Gulf Stream is observable in the occurrence of Eriocaulon 

 septang^dare, With., SisyrincMum anceps, Car., and Naias Jlexilis, 

 Rostk, upon the western coasts. It seems, indeed, possible that 

 the part played by this great current in the phenomena of distri- 

 bution has not been brought into sufficient prominence. The evi- 

 dence, though limited, suggests the enquiry whether, in addition 

 to some local plants, others, common to the two continents, and 

 fairly diifused, at the present day, in Europe, may not have had 

 their starting .points on its west shores, whither their seeds have 

 been carried, by the Gulf Stream, from America, at stray times, 

 during passing centuries, without destroying their vitality. 



VOLCANOES AND EARTHQUAKES. 



ABSTRACT OF A LECTURE 

 By T. Sterry Hunt, LL.D., P.R.S.* 

 It is proposed, in the present lecture, to discuss the nature and 

 causes of volcanoes and earthquakes, with their related pheno- 



* Delivered April 22, 1869, before the American Geographical and 

 Statistical Society, and reprinted from its proceedings. 



