540 FRANK E. BEDDARD. 
Fic. 20.—Embryos of the various stages described in the text, of the 
natural size. 
Fie. 21.—Nephridium of Stage A, displayed for nearly its whole course. 
J. Funnel. s. Seta sac. 
Fic. 22.—Section through head end of embryo of Stage B. NV. p. External 
orifice of mucous gland. f£ Funnel of the same. pf. Pharynx. The seg- 
ments are numbered, the figures being opposite to the sete. 
Fic. 23.—Embryo of Stage A. 
Fie. 24.—Lougitudinal section through function of stomodeum and mes- 
enteron in embryo of Stage C. f. Peritoneal cells. c. Cilia, covering a few 
cells of the mesenteron. 
