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XXIII. Illustrations of the Relationships existing amongst Natural Objects, 

 usually termed Affinity and Analogy, selected from the Class of Insects. 

 By J. O. Westwood, Esq., F.L.S., 8^c. 



Read January 17th, and May 2nd, 1837. 



AN the fourteenth volume of the Transactions of the Linnean Society is con- 

 tained an interesting paper by the Rev. W. Kirby, with the title, " A Descrip- 

 tion of some Insects, which appear to exemplify Mr. William S. MacLeay's 

 Doctrine of Affinity and Analogy," wherein the reverend author points out 

 the confusion which has occasionally arisen in attempts made to distribute the 

 objects of nature according to their natural relations, in consequence of the 

 authors of such attempts having no clear perception of the distinctions which 

 exist between the two kinds of relations above mentioned, and therefore con- 

 founding them together, or even occasionally giving the higher rank to rela- 

 tions of analogy instead of affinity. 



The object of the following remarks is still further to illustrate the theory 

 in question, and to show that from the entirely relative and comparative na- 

 ture of these relations, founded as they both are upon more or less perfect 

 resemblance, two animals may at the same time be allied together both by 

 affinity and analogy ; in other words, two animals may possess totally inde- 

 pendent relations both of affinity and analogy : thus, whilst the goatsucker and 

 the swallow are related to each other by analogy when we look to the class of 

 birds alone, we find them related together by affinity when the comparison 

 is made between them both as birds with the bat amongst Mammalia. In 

 like manner, whilst the bat and the swallow are thus related together by ana- 

 logy as members of the classes Aves and Mammalia, they must be considered 

 to be related together by affinity as vertebrated animals when we compare 

 them with the dragonfly amongst the Invertebrata. 



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