No. I.] CONTRIBUTION TO INSECT EMBRYOLOGY. 



17 



edge of the organ itself appear to creep along under and a little 

 in the rear of the advancing serosal elements. I cannot here 

 go into greater detail without unduly increasing the number of 

 my figures. Nor is it necessary, since it will, I believe, be 



vr&l] 



.WlA. 



Fig. II. 



Diagrams illustrating the movements and envelopes of the Xiphidium embryo. 

 D, the stage of the shortened embryo on the dorsal yolk ; E, embryo returning to 

 the ventral surface ; F, embryo nearly ready to hatch, ch., chorion ; bl. c, Blasto- 

 dermhaut ; sr., serosa; ind'^, outer indusium ; ind'^, inner indusium ; ind'^ -\- am., 

 inner indusium and amnion fused ; am., amnion ; ind^ c, cuticle of the inner 

 indusium ; ind^ s., granular secretion of the inner indusium ; am. s., amniotic 

 secretion ; v., yolk ; cl., columella ; gb., germ-band. 



acceded that the process briefly described in the above 

 paragraph, though now occurring in comparatively few 

 embryos, is very probably the more primitive process, whereas 

 the slurring observed in so many cases is to be attributed to an 

 unquestionably rudimental condition of the organ. 



