THE GLASS-CRABS OR PHYLLOSOMATA. 



307 



79, J5), had gradually in the pupa (Fig. 79, F, G) assumed 

 the opposite curvature. Its dimensions are threefold those 

 of the embryo, and it exhibits vivacious movements when ex- 

 tracted from the pouch of the parent. It is not improbable 

 it may yet undergo another change of integument before ac- 

 quiring the full form of the adult. 



Thus it appears that, in 3fysis, the jYau])lius-stage (Fig. 

 79, D, E) is passed over so rapidly that the embryo has gone 

 through it at a very early period, and nothing but the cuticu- 

 lar sheath of the body appertaining to this stage remains to 

 prove its existence. A step further, in the abbreviation of 

 the iVat^iws-stage, and there would be nothing to distin- 



■m 



Fig. SO.—P/iyllosoma.—A, ventral view of the body, with the limbs I'-XX' of the 

 left side and the bases only of XI' to XIII' represented. B. side view of the 

 body. C, the nervous system. Z>, the last cephalic and first and second thoracic 

 limbs. 



guish the general course of the development of Mysis from 

 that of Astacus. On the other hand, another Schizopod, 

 Ewphausia, has been shown by Metschnikoff ' to leave the 

 egg as a true Nauplius. 



1 Zeitschrift fur wlss. Zool., 1871. 



