68 



OTHER 'MYRIAPODS' 



geneous a group as the Symphyla. The larva slowly and laboriously 

 works its way out of the egg through the cut made in the blastoder- 

 mic cuticle and chorion by the two pairs of sharp spines at the 

 bases of the antennae. These spines are part of the embryonic 

 cuticle and are rejected with the latter at eclosion. During the 

 first few hours of freedom the larva enlarges, evidently by inges- 

 tion of fluid from without. For the first day it crawls sluggishly 



Fig. 16. Stages in the development oi Sciitigerella immacidata. 

 (After Michelbacher, 1938.) 



over the decaying vegetation on which it feeds, but thereafter be- 

 comes more active. After 7-12 days it retreats to the shelter of 

 some secluded crevice and there moults. With the sixth moult 

 the organism receives all its morphological parts, but complete 

 differentiation does not occur until a much later period, the life- 

 history being rather complex. After each moult more segments 

 are usually added to the antennae and broken antennae are re- 

 generated. This has been observed in individuals nearly three 

 years old. As already mentioned, the total life span may exceed 

 four years. 



