THE CUIBF COLEOPTEROUS FAUN^15. 3 



withstanding the accessibility of Madeira to the introducing 

 agencies of man (to which most of the other introductions are 

 referable), it becomes still more difficult to conceive of the dis- 

 semination of that kind of beetles by agencies independent of 

 man. 



But besides the advantages which the structure, habits, and 

 economy of beetles give for the interpretation of their geographi- 

 cal distribution, there is another important speciality inherent in 

 them which I shall amply illustrate in the course of this paper, 

 and which renders them peculiarly available for the study of its 

 problems, viz. a long-enduring persistency of form by which the 

 same type has been preserved through diverse modifications during 

 many geological epochs. This peculiarity is shared by all other 

 insects, as well as in different degrees by all beings of inferior 

 organization ; and the consequence is that in trying to make out 

 the past history of a country through its fauna and flora, we 

 must take each class of beings by itself and study its relations 

 separately, or we shall run the risk of confounding events belong- 

 ing to different dates. To do otherwise would be like attempting 

 to compile a history of England by combining the political history 

 of one age with the ecclesiastical of another and the scientific of 

 a third. The mammalian fauna took its present form long after 

 the insects had received theirs, and these earlier-dated forms 

 should therefore he able to tell of events long antecedent to what 

 the mammals could speak of. The relations of each must there- 

 fore be studied independently, and it is only after all shall have 

 been separately deciphered that the conclusions respectively drawn 

 from each can be brought together and some common general 

 result arrived at. In the meantime, by endeavouring to ascertain 

 the relative date of appearance of insects of various types in dif- 

 ferent countries, we may be able to assign the order of precedence 

 of a succession of events whose occurrence we can scarcely doubt, 

 but whose order of date we could not otherwise guess at. 



My purpose in the present paper is to submit some infer- 

 ences of this nature from a general view of the geographical dis- 

 tribution of the Coleoptera, indicating a somewhat different ar- 

 rangement of land and water in ancient times from that which is 

 usually supposed, and to strengthen these inferences by references 

 to what seem to me corresponding facts in other branches of na- 

 tural history. 



The first point to which 1 shall direct attention is the very in- 



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