182 



EMBRYOLOGY OF INSECTS AND MYRIAPODS 



The 

 figured 



embryonic development of the collembolan Anurida maritima as 

 and described by Claypole (1898) agrees in most particulars with 



that of Isotoma cinerea as outlined 

 above. Philiptschenko (1912) 

 points out a few discrepancies 

 which he ascribes to differences in 

 interpretation. 



It is conceivable that the 

 "diffuse" middle strand here 

 described together with the cell 

 masses that surround the stomo- 

 daeal and proctodaeal rudiment 

 constitutes the preprimordium of 

 the entoderm and that cells im- 

 mediately adjacent represent 

 mesoderm. 



DIPLURA 



Campodea staphylinus Westw. 

 Campodea staphylinus 



abd4 



proc 



Fig. 99. — Isotoma. Oblique frontal sec- 

 tion of posterior end of body, (abd) Abdom- 

 inal appendages, (gc) Germ cells, (mus) 

 Muscle, iproct) Proctodaeum. (yc) Yolk 

 cells. 



IS a 

 slender insect about 6 mm. long 

 living in damp places under stones 

 or in rotten wood and leaves. 

 The species occurs in Europe, but members of the genus occur also in the 

 United States. The eggs, according to Uzel (1898), are laid during the 

 warmer months in clumps of four or five or, less commonly, either fewer or 



■-^bld 



% 



% 



^ 





Fig. lOU. — ('nmpoden. Section of 

 egg with germ disk, (hid) Blasto- 

 derm. 



Fig. 101. — Campodea. Section of 

 egg with germ disk. 



more. One egg of the clump is stalked to form a supixjrt for the entire 

 cluster. The egg, which is spherical, measures about 0.4 mm. in diameter. 



