

INTRODUCTION. 



The sequence which exists between law and natural 

 phenomena must ever force itself interestingly on the 

 attention of the earnest thinker. Pleasure must be 

 felt in intelligently tracing the unmistakable signs of 

 consistency and unity throughout the vast system in 

 which man himself finds he is a mover. This oneness 

 is well expressed in the Greek word Kosmos, and its 

 correlative word Universe. 



The insect-world, containing more than one hundred 

 thousand species, is in itself a microcosm ; but the 

 multiplicity of its parts bewilders the student. It is 

 only by a subdivision of labour and concentration of 

 attention on the life-history of groups, that we can 

 hope successfully to trace the complex rising out of 

 the simple; or to note degradations of form effected 

 tbrough the disuse of parts or other like causes. 

 Abnormal developments or growths that may come 

 through the slow but persistent action of the environ- 

 ment or other influences on an animal's economy, may 

 well be studied in single biological groups, and thus 

 additional material may be gathered to permit of future 

 generalisations. 



Probably the ordinary scope of a Monograph is the 

 description of the forms, life-history, distribution, etc., 

 of the species contained in it. This wiU be a chief aim 

 of this treatise, but at the same time, whilst the scientific 



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