APPENDIX. 



705 



Fig. 654. 



Vis;. 055. 



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; r .\ , 



supraoesophageal ganglioi. ; 



n, nervous cord ; ga and t/, 



genital organs ; ??is, bands of 



muscles) is attained bymeanc 



of a moult, as usual in the 



metamorphoses of insects. 



The cells of the inner layer of 

 the skin 

 ( hypoder- 



iiis) now multiply greatly, and give rise to 

 at what corresponds to the primitive band of 

 the embryos of other insects. The third 

 larvr.l form is of the usual shape of ich- 

 neumon larvae. 



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 thir "! str.ge (Fig. 

 655, trj< three pairs of abdomimi tubercles 

 destined to form the ovipositor \ /, rudiments 

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

 at, rudiments of the antennae, Jl, irnaginal 

 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 lar\- cr' Platygaster. 



tg 



Third larva of Polynema. 



