EXPLANATION OF PLATES. 153 



Fig. 9. Section through theblastopore, showing the origin of meso- 

 derm and endoderm. The section is obliquely transverse. 



Fig. 10. Embryo after the closure of the blastopore and the forma- 

 tion of the optic lobes. Stage A. This should be compared with fig. 

 1, pi. II, of my paper on the development of the compound eye in 

 Whitman's Journal of Morphology, Vol. I. 



Fig. 11. Stage!?. Characterized by the development of the mouth 

 (m), antennulsB (7) and the abdominal fold (a/). 



Figs. 12 and 13. Side and ventral views of stage G in which the 

 antennae. (If) are outlined. 



Fig. 14. Ventral view of stage D. The mandibles (7/1) are out- 

 lined. 



Figs. 15 and 16. Ventral and lateral views of stage J3, characterized 

 by the existence of seven pairs of appendages. 



Figs. 17 and 18. Ventral and lateral views of stage P. 



Fig. 19. "Dorsal organ" of stage C in transverse section. 



Fig. 20. Stage G, removed from the chorion. 



Fig. 21. Surface view of the heart of stage G showing the ostium 

 of one side. 



Fig. 22. Telson of stage G. 



Fig. 23. Stage H; the embryo is nearly ready to hatch ; the gills 

 are budding from the bases of the sixth and seventh pairs of appen- 

 dages, and nerve cells have made their appearance in the walls of the 

 heart. 



Fig. 24. Mandible of stage H. 



Fig. 25. First maxilla of stage 77. 



Fig. 26. Second maxilla of stage 77. 



Fig. 27. Young shrimp after hatching, taken with a surface net. 



