DEVELOPMENT OP THE ANTENN.E OF TERMITES. 291 



bulk of the body. The break in the sei'ies will be observed 

 to occur between 0"75 and 0*84 nnn,, and it will he seen that 

 practically half of the soldiers were of the intermediate size. 



It is not usual among termites for the soldiers and workers 

 to be decidedly larger than the imagos, and therefore tlie 

 exceptional!}^ large soldiers of P. allocerus may be atavistic, 

 and indicate the evolution of the species from a larger 

 ancestor. Further, in those species where the soldiers and 

 workers approach the size of the imagos, and even with some 

 where both soldiers and woi-kers are relatively small, larger 

 individuals may exhibit antennse of more joints than do their 

 lesser companions. This is not the rule with this Psammo- 

 termes. It is true that the largest individual measured 

 possessed antennas of the same number of joints as the imago 

 (fig. 14, /), but the others had fewer, and there is little relation- 

 ship between the size of the individual and the number of 

 joints in their antenna. 



The range given in the antennal index for the soldier caste 

 is based upon a count made of the number of joints in 91 

 antennae. This on analysis showed XIV to be the common 

 expression, but there were many of XII, XIII and XV. 



Generally companion antennas are composed of the same 

 number of joints, but asymmetrical alliances are quite frequent, 

 the combinations met with being XV-XIV, XA-XllI, 

 XIV-XIIl, XIV-XII, XIV-X and XII-XI (see fig. 14, h, I, n, 

 o,q,s). 



Nearly all soldier antennae agree as regards their pattern 

 and are characterised by a swollen joint. III, and depart 



