DEVELOFMKNT OF 'I'HP] ANTENxNT.E OF TERMITES. 269 



common to the imago. Fig. 6, f, of the series represents the 

 XIX expression of the major soldier. Botli the XVIII [g, h) 

 are derived from the XIX by a (15 + li) union, whilst the 

 XYIII (0 is due to a (III + 16) union. The XVII (./) is due 

 to two unions, a (15 + 14) accompanied by a (111 + 16). 



The Homologies. — These are set out in fig. 6, k~t. All the 

 figures employed are from camera-lucida sketches, but are 

 not absolutely in proportion. With the exception of the 

 antennse of the minor workers it), all represent the same 

 degree of development — that is, the flagellum of each con- 

 tains the same quota of joint-elements, namely twenty-one. 

 In the flagellum of the ininor worker there are, however, 

 only 19 elements. The main point of difference between 

 the antennae of the major Avorker and imago is that in one 

 there is a constant (15 + 14) union which is always absent 

 from the latter. The main points of agreement between the 

 organs of the major Avorker and major soldier lie in the 

 frequency of the (15 + 14) union in the soldier organ and the 

 peculiarly attenuate nature of (13) and (12) in both. 



The XVII expression of the major soldier (fig. 6, r) is quite 

 uncommon, but homologises Avith the constant XVII of the 

 minor soldier (.§), as a compai'ison of the two sketches shoAvs. 

 The antenna3 of the minor woi"kers, as represented by {t), 

 shoAv their curtailment by the absence of (16) and (17). In 

 a feAv cases they must be regarded as XVIII-jointed as (14) 

 and (15) are practically independent joints. 



Development. — The natal condition of the antenna is as 

 represented by stage C (PI. XV), in which III is in a bilocular 

 phase. This seems common to all undifferentiated larvas at 

 the beginning of the first instar. 



Imago. — The antennte developing along the main route 

 C to M become XlX-jointed by the abjunction of (16), leaving 

 III composed of (0000 + 17) as in stage Nb. This is the more 

 common antenna; in it (16) the conventional IV is usually 

 large and might be taken as a development to MiV. Its true 

 condition, however, is revealed by the internal arrangement 

 of the elements of III Avhen in the last nymphal instar. 



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