876 



RADIAL AND ZYGOPTEKID SECTORS, »tc., 



The followins: table exhibits the results obtained : — 

 Table of Genera examined for Wing-Tracheation. 

 (N = Needham, R = Ris, T = Tillyard.) 



2. The Ontogenetic Evidence. (Text-fig. 2). 

 In the table given above, the genera marked * are those in 

 which more than one larval instar has been examined. In the 

 Zygoptera, it has not been possible to examine more than the 

 four last larval instars (which I have done in Austrolestes), owing 

 to the delicacy of the tracheJB. In the earliest examinable stage, 

 R is simple and unbranehed in Zygoptera, and remains so up to 

 the last larval instar. Very different is the case with the An- 

 isoptera, in which Needham (1, Fig. 1 ) has shown that, at the 



