Ixiv 



Here we have indications of an introduction of forms at a still 

 more remote epoch. In many cases the modifications of structure 

 have heen so great as to produce distinct generic forms, while 

 these remain still allied to winged European genera. In other 

 cases, however, the modifications are still greater, and the affinities 

 are with groups which in Europe are wholly apterous. Such 

 cases as Hadrus and Macrostethus, which belong to small groups 

 of wholly apterous genera, are difficulties on the theory of trans- 

 mission over the sea. But two considerations render this difficulty 

 less real than apparent. They all carry us back to a very remote 

 epoch ; and, knowing what we do of the instability of the apterous 

 condition, we may fairly conclude that the groups in question 

 were, at that time, in a partially winged state. At or near this 

 same remote epoch, the Madeiran group, as indicated by the 

 submarine bank now connecting the several islands, probably 

 formed one more extensive island, and the distance of ocean to be 

 traversed would then have been considerably less than it is now. 



If the various groups of facts which I have here set forth, 

 respecting the distribution of apterous and winged species and 

 genera, are fairly considered as a whole, I think they will be seen to 

 be quite inconsistent with the theory of that distribution having 

 been effected by a former land-connection with Europe ; and, 

 considering that we are necessarily ignorant of many of the waj^s 

 by which organisms are transmitted across ocean barriers, such 

 transmission seems to be indicated in the case of the Madeiran 

 Coleoptera, not by means of drift wood and ocean currents, which 

 Mr. Murray thinks must be the most efficient means of transport, 

 but b}' some mode in which their wings are called into play, which 

 can only be by a passage through the air when assisted by gales 

 and hurricanes. 



There is one other group of islands which seems well adapted 

 to offer a crucial test of the correctness of the theory of land- 

 connection. The Azores are more than twice as far from Europe 

 as the Madeiras, and, what is of still more importance, they are 

 cut off from it as well as from the Madeiras by a broad belt of 

 ocean of the enormous depth of nearly 15,000 feet. We may feel 

 pretty confident, therefore, that if both groups have once been 

 united to the continent, the separation of the Azores is by far the 

 more ancient event ; and any theory which requires the Azores to 

 be the most recently separated must be strongly supported by 



