30 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I42 



Tlie only intrinsic muscles of the antenna are those in the scape 

 inserted on the base of the pedicel. The flagellum is thus moved by 

 the pedicel muscles, and the pedicel might therefore appear to be a 



Fig. 14. — Types of adult insect antennae. 



A, Isotoma paluslris, Collembola (adapted from Imms, 1939). B, Diagram of 

 typical thysanuran-pterygote antenna. C, Leucopelea albescens, lamellicorn 

 beetle. D, Xylovia tenthredinoides, Diptera-Xylomyidae. E, Tabanus affinis, 

 Diptera-Tabanidae. F, Archytas apicijer, Diptera-Tachinidae. G, Sarcophaga 

 bullata, Diptera-Sarcophagidae. 



basal annulus of the flagellum. It is noted by Imms (1940), however, 

 that growth of the antenna never involves subdivision of the pedicel. 

 The pedicel contains an elaborate sense organ known as the organ 

 of Johnston, so it is probable that the pedicel itself is a segment from 

 which the muscles of the flagellar segment have been eliminated. 

 The flagellar units vary in size from short annuli to long sections. 

 If we are not too particular about hybridizing words, they may be 



