262 CLAUDE FULLER. 



(10-11), (12-13), (14-15), (16-17). In the series the cycle 

 of external and internal metamorphoses of joint III is 

 recorded and the difference between a joint in posse and a 

 joint in esse is illustrated by the notation. Thus the differ- 

 ence between diagram A and diagram B is that the sister- 

 joints (8-9) are numbered in B because they have abjuncted 

 and are to be regarded as separate entities, whereas in A they 

 are the two distal loculi of joint III. This also explains the 

 difference between a pseudo-XII-jointed and a definitely 

 Xll-jointed expression. 



Hypothetically, an organ may be arrested in any one of 

 the phases or stages A to P. A-^ery frequently, however, they 

 are arrested in a transition from one stage to the next. Thus 

 P represents a pseudo-XXII-jointed organ, and this becomes 

 XXI when only the distal loculus abjuncts. This arrest in 

 transition is illustrated by diagram Pb, and represents those 

 cases where an organ progressing to an even total of joints 

 becomes odd-jointed. Thus Nb is a XlX-jointed organ derived 

 from a pseudo-XX, Kb a XVII from a pseudo-XYIII, and Lb 

 a XV from a pseudo-XVI. 



Other variations are due to the ab junction of the two 

 loculi of III as a compound joint ; thus diagram AB shows an 

 Xl-jointed expression derived from the pseudo-XII of A as 

 the result of the union of the first pair of sister-joints (8-9) ; 

 D^ shows the abjunction of the second pair of sister-joints as 

 a compound (10-11) ; it is described as DE because it is 

 derived from D and is elementally homologous with E. The 

 same applies to G//, JK and MV. The development of antenna? 

 may or may not continue after such a compound has 

 abjuncted. The most extraordinary cases of this occur in the 

 antennae of Termes Avaterbergi, especially those of the 

 imago. These are not charted. The more common develop- 

 ments taking place after the fusing of two joint elements to 

 form a compound joint are illustrated by the series GH to GL 

 and 3K to JO. 



A comparison of Kb, K, jK, GK and Giv b shows five forms of 

 antennfB all differently composed 3'et elementally homologous. 



