DEVELO?IV[EI«JT OF TUK ANTEISN/E OF TEliMn'KS. 261 



Part II: SYSTEMATIC REVIEW. 

 1. INTRODUCTION. 



In this part an attempt is made to set out concisely an 

 account of tlie antenntB I have examined. The vainations 

 met with are discussed and tlie different compositions found 

 in each species are homologised. Ordinarily, under a 

 separate heading*, some account of the development of the 

 organs is given, and each is based as far as practicable upon 

 serial examinations of the organs of the developing forms. 

 Unfortunately, however, the material for certain stages was 

 very limited in some cases, and often, where a great many 

 antennte were studied, the result in the aggregate was no 

 great compensation for the task. 



It was my intention, at the outset, to supplement each 

 discussion with a complete series of drawings. This, how- 

 ever, would have resulted in a multiplicity of many figures 

 bearing so much likeness to one another that they could only 

 lead to confusion. The homologies of the antennas have, 

 therefore, been illustrated by outline figures prepared from 

 camera lucida drawings. When conveniently possible the 

 various antennas of a species are drawn in proportion. 



Illustrations of the developing organs in the different 

 species have been practically eliminated, as it was found 

 possible to arrange all cases in a composite chart. This is 

 given as Plate XV. The chart comprises thirty-seven 

 diagrams and represents the phases of development Avhich 

 come under reference. For the sake of convenience and con- 

 ciseness these phases are referred to in discussing a given 

 development as " stages," and in both chart and in the 

 discussions these are treated very much as one does a genea- 

 logical statement. The main route of development for a 

 hypothetical XX or pseudo-XXII-jointed organ is traced 

 through its various phases from a X, pseudo-XII-jointed, 

 ■condition in the sixteen diagrams A to P, the increase being 

 represented by the insertion of the five pairs of joints (8-9), 



