ARTHUR DEWITT WHEDON 373 



THE COMPARATIVE MORPHOLOGY AND POSSIBLE 



ADAPTATIONS OF THE ABDOMEN IN 



THE ODONATA 



BY ARTHUR DEWITT WHEDON 



CONTENTS 



Introduction 374 



Problems suggested by variation in the abdomen 374 



Definition of the present problem 375 



The materials studied and their preparation 376 



Acknowledgments 378 



Comparative anatomy 378 



A review of general anatomy with special reference to the tj'pes 



studied 378 



Larvae 380 



Imagoes '. 378 



The groups compared 380 



External anatomj- 381 



Modifications in size 381 



Modifications in shape 385 



Table of abdominal dimensions 387 



Internal anatomj^ _. 389 



Review of earlier work 389 



The morphology of the larvae 390 



I. Zygoptera: Calopteryx, Hetaerina, and Lcstet^ 390 



II. Anisoptera: Aeshninac: Ariax 400 



III. Anisoptera: Libellulinae: Tniined, Lihelliiln, Platheniis 



and Sympctrum 408 



The morphology of the imagoes 413 



I. Zygoptera: Calopleryx, Megaloprcpas, aiul fAsli-.-i 413 



II. Anisoptera: Aeshninae: Anax and Aeshna 418 



III. Anisoptera: Libellulinae: LibeUnla, Plalhcmi!i, Erylhc- 

 tnis, Perithemis and Tramca 422 



Summary of comparative anatomy 422 



Abdominal modifications as adaptations 425 



Flight 426 



Copulation and oviposition 428 



Respiration 429 



Bibliography 430 



Abbreviations used in Plates .' 433 



Explanation of Plates 435 



TRANS. AM. ENT. SOC, XLIV. 



