484 president's address. 



There are, as you know, a particular set of Coleoptera which 

 affect the seashore ; they are not very numerous at any locality, 

 but among them are genera which are represented in almost every 

 country of the globe. Such genera are called cosmopolitan, in 

 distinction to those which are found only in particular districts. 

 Several of these genera contain species which are very nearly 

 allied, or sometimes in fact undistinguishable and therefore iden- 

 tical along extended lines of coast. 



Now it happens that some of these species, though they never 

 stray from the ocean shore inland, are capable of living upon 

 similar beaches on fresh water lakes, and a few are found in local- 

 ities which are now quite inland. 



To take an example, or rather several examples together, for 

 the force of the illustration will be thereby greatly increased. 



Along the whole of the Atlantic, and the greater part of the 

 Pacific coast of the United States, is found in great abundance on 

 sand beaches, a species of Tiger-beetle, Cicindela hirticollis, an ac- 

 tive, winged and highly predaceous insect ; the same species occurs 

 on the sand beaches of the great lakes, and were it confined to these 

 and similar localities, we would be justified in considering it as living 

 there in consequence solely of the resemblance in the conditions 

 of existence. But, it is also found, though in much less abun- 

 dance, in the now elevated region midway between the Mississippi 

 and Rocky Mountains. Now, this_ is the part of the continent 

 which, after the division of the great intercontinental gulf in Cre- 

 taceous times, finally emerged from the bed of the sea, and was in 

 the early and middle Tertiary converted into a series of immense 

 fresh water lakes. As this insect does not occur in the territory 

 extending from the Atlantic to beyond the western boundary of 

 Missouri, nor in the interior of Oregon and California, I think 

 that we should infer that it is an unchanged survivor of the spe- 

 cies which lived on the shores of the Cretaceous ocean, when the 

 intercontinental gulf was still open, and a passage existed, more- 

 over, towards the south-west, which connected with the Pacific. 



The example I have given you of the geographical distribution 

 of Cicindela hirticollis would be of small value, were it an isolated 

 case; nor would I have thought it worthy of occupying your time, 



communication of important truth. * This insect, which I have se- 

 lected as a type for illustrating the methods of investigation to 



