250 CLAUDE FULLER. 



any beyond it and may be even longer than II. In some, 

 III is particularly long and somewhat clavatO; when it fore- 

 shadows the third segment of the three-jointed scape of the 

 specialised insect-antenna. In this striking form it is exhibited 

 by the soldiers of Calotermes durbanensis. The antennae 

 of the imagos of this species occasionally exhibit III in the 

 long clavate condition and it appears common to the imago 

 antennae of Rhinotermes putorius. Subsequently it will 

 be shown that III of the adult organ is the repository of joint 

 elements, and is in the wide sense a compound joint, variable 

 as regards the joint elements it contains, because it represents 

 the variable arrest of the formative zone. 



By the suppression of an articulation one joint of the 

 flagellum becomes ankylosed to another. Sometimes such 

 ankyloses are aberrant and occasional, but on the other 

 hand unions resulting from the fusing of sister elements may 

 occur with sufficient regularity to become either specific or 

 subspecific. The extent to which an articulation is suppressed, 

 even when union occurs with characteristic regularity, is in 

 some cases very variable, and ranges from a simple ankylosis, 

 in which both segments retain their individuality, through all 

 stages of combination to complete fusion. All these phases 

 of union may occur in the antennse of the individuals of one 

 caste. 



(2) The Notation of Joints. 



In describing the composition of an antenna and the 

 development of joints the conventional numbering of each 

 segment from base to apex has grave disadvantages. It is, 

 however, an established method and one impossible to discard. 

 Further, the giving of the total number of joints for variable 

 antennas as an unqualified criterion is open to objection 

 because it so often conveys a false impression of the nature 

 of the organs. To number the joints in the sequence of their 

 origin would be a very irksome matter, as those of the scape 

 would be I and II, the apical III, the penultimate lY, and 

 so on back to the scape. 



