318 NATURAL HISTORY OF THE BERMUDAS. 



with dark brown, upwards of a third of an inch wide at 

 the angle. Under-wings rounded, and externally bordered 

 with dark brown. Colour of surface, bright sulphur yellow. 

 Primary wings, paler yellow on the under side, with a 

 central black point. Outer border, near the fringe, tinged 

 with ferruginous. Secondary pair same colour, marked 

 with one, and sometimes two, black points near the centre, 

 and sprinkled with small patches and particles of ferru- 

 ginous. Female, pale yellow. 



I glean from letters received from my friend, John 

 Mathew Jones, dated from Halifax, Nova Scotia, the 7th 

 of August and 7th of September of the present year 

 (1875), that a vast flight of Terias lisa, consisting of 

 millions of those insects, was observed on the 1st of Octo- 

 ber, 1874, "far out at sea," viz., six hundred miles from 

 the coast of America ; and that this marvellous host of 

 Butterflies was enabled to reach the islands of Bermuda. 



Let us attempt to enquire how, and by what natural 

 means, this extraordinary and wonderful accumulation of 

 American Lepidoptera were assembled together, and 

 moved across so wide an expanse of ocean, at a season 

 of the year well known to be subject to storms of great 

 violence. 



The problem is somewhat wide, embracing as it does, 

 the natural history of that particular Butterfly, and some 

 knowledge of the winds which blow in the latitudes 

 wherein this remarkable phenomenon is said to have 

 occurred. 



Terias lisa is common, I believe, to the southern 

 portion of the United States. My acquaintance with this 

 Butterfly dates from the 10th of October, 1847, upon which 

 day it suddenly appeared in great abundance at, and near, 



