Bull. U. S. B. F., igr;; 



Plate XVII. 



Fii;, I. — Mature o\uiii. x 45, 



Fig. 2.— 0\-um with early blasluderm. x 45; B. blastoderm. 

 Fig. 3. — Ovum with later blastoderm, x 4:;; C. cleavage cavity. 



Fig. 4.— Ovum with blastoderm, showing embryonic shield, x 45; £^5, embryonic shield; £-4 , embryonic area; Gi^.germ. 

 ring. 



