262 BUMPUS. 



EXPLANATION OF PLATE XIX. 



Fig. i. Surface view of egg in stage represented on PI. XIV., Fig. M. X 6a 



Fig. 2. Portion of a section through a segmenting egg which contained but two 

 nuclei. X 50. 



Fig. 3. Section of an egg in stage represented on PI. XIV., Figs. D and E. X 50. 



Figs. 4-1 i. Transverse sections made through embryo, as indicated by horizon- 

 tal lines in Fig. 1 (5—5 to 11 — 11). X 200. The ectoderm is represented in a 

 deeper and the entoderm in a lighter shade of gray. Fig. 11 represents, in the 

 median line, a section through the anus. 



Fig. 12. Longitudinal section through the embryo, as indicated by the line 

 12—12 in Fig. 1. X 200. 



Fig. 13. Longitudinal section through median line of Fig. 1. 



