252 BUMPUS. 



EXPLANATION OF PLATE XIV. 



The figures are enlarged about thirty-five diameters, and represent fresh eggs that 

 have been treated with dilute nitric acid. 



Fig. A. Surface view of an egg that is not infrequently found associated with 

 eggs similar to B, C, and D. Certain ovarian eggs present a similar structure 

 (PI. XVI., Fig. i). 



Fig. B. An egg before segmentation. The funiculus is represented by the whitish 

 patch outside the egg-membrane. 



FlG. C. Surface view of an egg undergoing segmentation. (The lithographer has 

 represented the blastomeres incorrectly. They are but slight elevations, and are not 

 so clearly separated by deep furrows.) 



Figs. D and E. " Morula stage." Two views of the same egg. The polar glob- 

 ules at R-k are not sufficiently distinct. 



Fig. F. Egg in blastula stage. Deeper colored yolk-laden cells are shown 

 at Ye. 



Fig. G. Surface view of egg in process of gastrulation. 



Fig. H. First appearance of the embryonic area. 



Fig. /. The lithographer has failed to give the extremely delicate and indefinite 

 outline that is presented by the embryonic area of eggs in this stage. The region 

 posterior to the blastopore is, in reality, but little more distinct than in Fig. H. The 

 formative centres of the second antennae are represented by the lateral extensions 

 lying in a plane immediately in front of, and lateral to, the telson, T. 



Fig. J. Surface view of an egg, showing the details of the embryo more clearly 

 outlined. Compare PI. XVII., Fig. i. 



Figs. K and L. Stages showing the contraction of the embryonic area. 



Fig. M. Stage of greatest embryonic contraction. The outline of the heart- 

 shaped cuticular flap is clearly shown. 



Fig. N. The " egg-nauplius " stage. 



Fig. O.-R. Successive stages in the development of the embryo. 



