554 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



PLATE XLVI. 

 (Stage IX.) 



FIGS. 1-16-151. Serial trausver.se sections, through the embryo 01 A. saulcyi, at the time when 

 pigmeut is first deposited in the, eye. In Fig. 146 the developmental history of the 

 retinal layer is well shown, x 230. 



FIG. 152. Nearly median longitudinal section of embryo in similar stage. x58. 



FIG. 153. Sagittal section of similar embryo, showing degenerating elements in yolk below dorsal 

 plate, x 58. 



REFERENCE LETTERS. 



A. 1, first antenna. 



A. II, second antenna. 

 Ab., abdomen. 



B. C., blood corpuscle. 

 B. S.. blood sp:ioe. 

 i-p., i';ir:i|>;lcT. 



Deg., degenerating cells. 



Dp., dorsal plate. 



End., endoderm. 



/(/., tbregnt. 



fa., fiber mass of nervous system. 



tj.lI-III, bruin. 



g. c., ganglion cell. 



(j.m.a., anterior gastric muscle. 



H., heart. 



ltd. , bypodermis. 



H</., hindgiit. 



Lb., labrani. 



Md., mandible. 



Mcs., mesoblast. 



Hfu.f., flexor muscle. 



oero., u-sophageal commissure. 



e.g., optic ganglion. 



O. L., optic lobe. 



jtk., punct substanz. 



pr., porineurium. 



Rt., retinogen. 



S. O. G., Bupra-oesophageal ganglion. 



T., telson. 



To., transverse commissure. 



Th., thorax. 



Vac., vacuole. 



/., yolk. 



f. C,, wandering cells. 



