APPENDIX. 



705 



Fig. 664. 



Fig. 655. 



temporary hook-like jaws (md) , moving about like a Cestodes 



embryo with its well known six hooks. The tail moves up and 



down, but is scarcely used in 



locomotion. The nervous and 



vascular systems and tracheae 



are wanting, while the alimen- 



tary canal is simply a blind 



sac, remaining in an unorgan- 

 ized state. 



The second larval state 



(Fig. 654, ce, oesophagus ; ng, 



supraoesophageal ganglion; 



n, nervous cord ; ga and gr, 



genital organs ; ms, bands of 



muscles) is attained by means 



of a moult, as usual in the 



metamorphoses of insects. 



The cells of the inner layer of 



the skin 

 ( hypoder- 



mis) now multiply greatly, and give rise to 

 what corresponds to the primitive band of 

 the embryos of other insects. The third 

 larval form is of the usual shape of ich- 

 neumon larvse. 



In Polynema the larva in its first stage 

 is very small and motionless, and with 

 scarcely a trace of organization, being a 

 mere flask-shaped sac of cells. After five 

 or six days it passes into a worm-like stage 

 and subsequently into a third stage (Fig. 

 655, tg, three pairs of abdominal tubercles 

 destined to form the ovipositor ; I, rudiments 

 of the legs ; /&, portion of the fatty body ; 

 a, rudiments of the antennae, fl, imaginal 

 discs, or rudiments of the wings). 



The larva of Ophioneurus is at first of 



the form indicated by Fig. 656 E. It differs from the genera 



already mentioned, in remaining within its egg membrane and 



Second larva of Platygaster. 



Third larva of Polynema. 



