The origin and develojjment of the wings of Coleoptera. 519 



of Comparative Zoology at Harvard University under the direction of 

 Dr. E. L. Mark. It was much extended in the Biological Laboratory 

 of Antioch College, and completed in the Hull Zoological Laboratory 

 of the University of Chicago. I take this opportunity to express my 

 appreciation of the many valuable suggestions received from the 

 Director of the Laboratory at Cambridge, Dr. E. L. Mark, and to 

 Dr. C. B. Davenport of the University of Chicago. 



II. Development of the Wings in Coleoptera. 



The wings of all of the more specialized orders of insects 

 are evaginations of the body wall into which there have migrated 

 tracheae, nerves and mesodermal tissue, producing in the aggregate 

 complex structures. In the Lepidoptera the development of the wing 

 has been followed instar by instar, so that we know in detail the 

 changes which occur in each stage. Moreover there is great uniformity 

 in the wings of Lepidoptera, both as to the time of first appearance 

 and as to their subsequent development, so that accurate comparisons 

 are possible. The same is partly true for the Diptera and the 

 Hymenoptera, but in the Coleoptera the amount of information con- 

 cerning wing development is meagre. Excepting the papers of Com- 

 STOCK & Needham (1899), Krüger (1899) and Needham (1900) which 

 are the only considerable attempts that have been made to study the 

 development of these organs in beetles, the literature on insect meta- 

 morphosis contains only scattered and incomplete notes and these are 

 entirely upon the later stages of wing development. 



Using Hippodamia JSpunctata Linn. (CoccinelUdae) as a subject, 

 CoMSTOCK & Needham (1899) found a type of wing development of 

 the same general character as that described by Gonin (1894) for 

 Pieris excepting that the condition of the tracheal system is much 

 simpler. Krüger (1899) worked upon Tenehrio molitor L. {Tenebrio- 

 nidae), Lema asparagi L., and L. merdigera {Chrysomelidae) and after 

 finding that the hind wings and elytra arise simultaneously and develop 

 in an exactly similar manner for a major part of the larval life con- 

 cludes that the elytra are divergent structures and not specialized 

 wings. I shall show in the following pages that while the type of 

 wing development found by Comstock & Needham (1899) is character- 

 istic for a certain group of beetles, it is in reality not a common one, 

 and I shall further show that the conclusions of KrIjger (1899) are 

 erroneous. 



