158 



DR. K. W. VERHOEFF ON BRACHYCHAETEUMA, 



constriction. It will be evident from what has been said 

 above, that no part in the increase can be taken by the broad 

 and spherical third joint of the first larva. The seven-jointed 

 Titanosoma antenna are then converted into eight-jointed 

 antennae through the second joint dividing once more into 

 two, as may be inferred from the fact that the second joint, in 

 the second to the fourth larvae, undergoes a lengthening, and 

 that in the fourth larva it is twice as long as the first and third 

 joints, and has no bristles on the basal half. The same con- 

 clusion follows moreover from the fact that in the fifth larva, 

 with eight-jointed antennae, the second and third joints are 

 each only slightly longer than the fourth, simply because these 

 second and third joints have arisen from the division of the 

 former second. With the complete material available, there- 

 fore, the development of the antennae in Titanosoma is clear 

 beyond any doubt, so that I am able to present it in the form 

 of the following table : — 



5-jointed antennas . 

 7- jointed antennae ... 

 8-jointed antennae 



In spite of the differences which have been described, the 

 following common features in the development of the antennae 

 in the Diplopods may be regarded as established : — 



1. The growth of the antennae is distinctively post-basal. 



2. The two last antennal joints (the seventh and eighth), 



including the sense organs of the last one, are already 

 developed in their final form in the first larva. 



3. The sixth antennal joint is also, at least as regards its 



distal half, developed in final form in the first larval 

 stage. 



4. The further constricting-off of joints in the basal half of 



the antennae may proceed in different ways, but the 

 original second joint always undergoes a division 

 later. 



1 2345 



1 2 34 567 



1 2 3 45 678 



