Al'PKNDIX. 



705 



Fig. 654. 



Fi.LT. (;.5.-). 



Platvf'aster. 



temporary hook-like jaws (7)icl), movinii; aboul like a (. vslodes 

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

 down, but is scarcely used in 

 locomotion. The nervous and 

 vascular systems and trachea? 



'' OS 



are wanting, while the alinien- «? 



tary canal is siaiply a blind 



sac, remaining in an unorgan- n 



ized state. 



Tlie second larval state 



(Fig. 654, OP., oesophagus; ^\ , 



supraoesophageal ganglioi ; 



n, nervous cord ; ga and (/, 



genital organs ; ms, bands of 



muscles) is attained by meanc 



of a moult, as usual in the 



metamorphoses of insects. 



The cells of the inner layer of 

 the skin 

 ( hypoder- 

 nis) now multiply,' greatly, and give rise to 



..- at what corresponds to the primitive band of 



the cml)ryos of other insects. The third, 

 larvrd form is of the usual shape of ich- 

 neumon larvit;. 



In Pohjm'ma the larva in its first stage' 

 is very small and motionless, and with 

 scarcely a trace of organization, being a 

 mei-e flask-shaped sac of cells. After five 

 or six days it i)asses into a worm-like stage 

 and subseciiiently into a thir '. str.ge (Fig. 

 655, tfj, three pairs of abtloinina tubercles 

 destined toformtheo, inositor , /. rudiments 

 of the legs ; fk, portion of the fatty body ; 

 at, rudiments of the antenme, ,//. iuuiginal 

 discs, or rudiments of the wings). 



The larva of OjihionenrKS is at first of 



the form indicated by P'ig. 656 K. It differs from the genera 



already mentioned, in remaining within its egg membrane and 



Second )ar\ 



Third larva of Polynema. 



