DEVELOPMENT OF THIO ANTENNii; OF TE R:\HTES. 



287 



The homologies of the antennje may be formulated as 

 follows : 



XIX : I II III (0000 + 15) IV (14) V (13) 



XVIII : I II 111(0000+15+ 14) IV (18) 



XVII : I II III (0000+15+ 14+ 13) 



XVI : I II III (0000 + 15+ 14+ 13H 



VI (12) VII (11) 



V (12) VI (11) 



IV (12) V (11) 



12) IV (11) 



It would seem, therefore, that the distinctions are not due 

 to the development of the organs heing arrested in an earlier 

 stage, but to the failure jof articulations to come into 

 evidence, so bringing about the fusing with III of rudimentary 

 joints. 



Soldier. — The antennas of soldiers invariably exhibit the 

 peculiar grossness and clavate shape of III; they differ in the 

 number of articulated joints in different individuals and on 

 the two sides. The details of variation are given in the 

 accompanying table : 



Symmetrical pairs. 



Asymmetrical pairs. 



XII joints . 



XIII ., . 



XIV ., . 



9 soldiers 

 9 ., . 

 5 



XI and XIII joints 



XII „ XIII „ 



XIII „ XIV „ 



XIII „ XV 



XIV „ XV 



1 soldier 



2 soldiers 

 1 soldier 

 1 „ 



1 „ 



The various antennae are represented in fig. 12, c-f. As 

 there is no decided difference in the length of III throughout 

 the series, fig. 12, c, is representative of all except such in 

 which III is noticeably compound as in (d) and (e), or in 

 which a long fused joint has formed about III, IV and V, as 

 in (/). It seems highly probable from the condition of the 

 organ of a wingless form, possibly a third instar soldier, 

 represented by (g), that joint-multiplication subsides at 

 different stages and is replaced by modificatiou ; ergo, the 

 dilation of III is due to the increase in the transverse 

 dimensions of the elements instead of one in their axillary 

 dimension. 



(1) Development. — The ab ovo expression is somewhat 



