PREFACE ix 



seems, therefore, to be in the highest degree advisable, that 

 Dr Latter's lead should now be followed in all Zoological 

 Laboratories, by the selection of two other Insect " types," which 

 should illustrate respectively the phenomena of incomplete and 

 complete metamorphosis. Of these, one should undoubtedly 

 be the Dragonfly, the other either the Wasp, Bee, Blow-fly or 

 Butterfly. 



The metamorphosis of the Dragonfly is easily observed and 

 easily understood, yet it is as striking as that of any other Insect. 

 If we add to this the further advantages that both larva and 

 imago (but particularly the former) provide dissections of com- 

 parative ease and unrivalled beauty: that both closed and open 

 tracheal systems can be studied in the one insect: and that the 

 adaptations to the aquatic way of living in the larva are of an 

 interest not to be equalled anywhere in the Insecta, it will be 

 seen that a very strong case exists for the recognition of the 

 Dragonfly as a second biological "type" for the Class. If this 

 book helps towards the general acceptance of this view, by pro- 

 viding a text- book suitable for the use of zoological students, 

 the author will feel more than repaid for his labours. 



Little need be said as to the design of the book. I have made 

 original text-figures in every case except where the material was 

 not available. In such cases, the authorship of the figure is 

 gratefully acknowledged, but the lettering has been altered to 

 suit the text of the book. Of the original drawings, figs. 23, 

 30, 33, 35, 37, 38, 125, 128, 139, 146 and 154 have already appeared 

 in my contributions to the Proceedings of the Linnean Society 

 of New South Wales [167, 169, 171, 172, 176], while figs. 79-83 

 are taken from a paper contributed to the Journal of the Linnean 

 Society of London [179]. 



Almost all the specimens studied and figured have been 

 collected around Sydney. Readers will therefore not fail to 

 discover a very strong Australian "flavour" in the book. Those 



