420 CLAUDE FULLER. 



correctly speaking, the failure to separate) of joints III and 

 IV ; because, if a series is searched for, every degree of non- 

 separation can be found from joints with two whorls of bristles 

 and distinct pseudo-articulations through joints with two 

 whorls of bristles and no trace of articulation to simple uni- 

 whorled segments giving no direct evidence of how they 

 orig'inated. That the XVII-iointed antenna is formed bv 

 the non-separation of joints V and VI of the XlX-jointed 

 form can be demonsti^ated just as readily. 



Turning to the soldier caste ample evidence can be found 

 to show that the XVII-jointed form originates as does the 

 XVI I- jointed major and minor worker form ; that is, by 

 finding pseudo-articulations and double whorls of bristles on 

 joint IV (or 5 4- 6 of the XlX-jointed antenna). In certain 

 nest-series there are soldiers which present XVI segments to 

 the antenna and all joints are complete and uni-whorled. 

 However, amongst them can be found (a) normal soldiers 

 with XVII-jointed antenna, {h) sometimes an abnormal 

 soldier with both a XVI- and a XVII-jointed antenna, und 

 (c) an abnormal soldier with both antennJB XVI-jointed, in 

 some of which III shows an intermediate ai'ticulation ; in 

 other words the joint III of the XVI-jointed antenna has 

 arisen through the non-separation of joints III, IV, V, and 

 VI of the XlX-jointed form. 



In this connection the segmentation can be deduced from 

 the larval forms of T. badius. The youngest condition 

 observed is the larval stage (1 to I'S mm. long) having ten 

 joints clearly expressed (Text-fig. 15, a). Joints I and II have 

 already acquired their fixed expression, and seven apical joints 

 are distinctly separate and joint III is elongate. Joint III 

 -then subdivides into three segments and gives a XII- 

 joitited antenna {h). It then elongates (c) and later subdivides 

 to give the XlV-jointed antenna (cZ). This shows that the 

 XlX-jointed antenna arises out of the growth and sub-division 

 of joint III. If there is no check in development, the extra 

 joints appear between III and IV of the X-jointed antenna 

 until the XlX-jointed form is fully expressed, and this, at 



