DEVELOPMENT OF THE ANTENN.E OF TERMITES. 289 



Imago. — The variation given for the imago in the antennal 

 index is based upon the examination of 49 organs. These 

 represented 19 pairs and 11 single organs. Of the pairs, 

 4 were asymmetrical, 3 being XVI-XV and 1 XA^-XII. 

 The last mentioned, XII, is only recorded as a matter of 

 interest, as it Avas essentially aberrant and prol)ably owed its 



Text-fig. 13. 



Cryptotermes sp. o-b. Imago, c. Soldier. tZ-/i. Developing antenna; 



origin to some injury — a most unusual factor. The table 

 shows the preponderance of the XY- and XVI -jointed organs. 



No. of joints 



Xo. of antennae 



XII XIII XIV XV XVI , XVII 



21 



= 49 



All arise from the phase of the nymphal antenna (fig. 12,, d), 

 which is about in stage E (PI. XY). If this develops to G and 

 (12) is abjuncted the XY organ results; if (12) and (13) abjunct 

 the organ is XYI -jointed (stage H). Should any development 



