i8 



less in these islands, and this remarkable fact is accounted for 

 in this way, that wings are not absolutely necessary for these 

 species, and, therefore, those insects which are frequent flyers 

 are blown out to sea, while the more sluggish individuals who 

 either cannot or will not fly remain to continue the race. 

 This process, continuing from generation to generation, would, 

 on the well-ascertained principle of selection and abortion by 

 disease, in time lead to the entire loss of wings by those insects 

 to whom wings are not a necessity. Those insects to which 

 wings are a necessity to obtain their food or to provide for their 

 offspring are found, in many cases, to have more powerful 

 wings than individuals of the same species in Europe. 



The lecturer then described the remarkable fauna of the little 

 island of St. Helena, and tried to show that its origin is also 

 Palseartic, although the island of St. Helena is situated 

 1,000 miles to the south of the Equator, and more than 1,800 

 miles south of the Cape Verd Islands. He pointed out the in- 

 timate connection between the insects found on St. Helena and 

 the Cape Verd and Canary Islands, and suggested that there was a 

 likelihood that in geological times there were many islands in 

 the Atlantic Ocean, bridging over this enormous distance, 

 whose former existence is now marked by rocks and shoals, 

 and that by means of these stepping-stones the aboriginal 

 inhabitants of St. Helena arrived. Also, that there is reason 

 to believe that during one of the glacial periods the ocean 

 currents in the South Atlantic were reversed, and that the 

 same cause would drive animals to seek more southern climes. 

 The insects and shells on the island of St. Helena are very 

 different from those found elsewhere. There are no mammals, 

 reptiles, or fresh-water fish, and only one species of land bird 

 found on it, showing that St. Helena has been disconnected from 

 other islands from an extremely remote time. 



