556 MEMOIKS OF THE NATIONAL ACADEMY OF SCIENCES. 



PLATE XLVII. 

 (Stage IX.) 



FIGS. 154, 155. Transverse sections through entire embrjo of Alpheus xaulcyi. In Fig. 154 a yolk 

 nest is cut. Blood spaces occur near tbe surface of the egg. x61. 



Fm. 15(5. Cell nest, containing degeneration products. Its position in the yolk is shown in Fig. 

 154. x 245. 



FIG. 157. Part of median longitudinal section through the thoracic-abdominal flexure. The grow- 

 ing endodermal epithelium and its fusion with the lining of the intestine are particu- 

 larly well shown. Wandering cells appear to be uniting with the endoderm. x245. 



FIG. 15S. Sketch of egg embryo, AlpJieua xnvlcyi, of same phase as that represented by Fig. 157. 

 X61. 



FIG. 159. Horizontal section through brain and eyestalks of a slightly older embryo. x61. 



FIG. ICO. Part of transverse section of similar embryo on level with the mandibles. x245. 



FIG. 161. Supcrticial part of section of egg, showing surface cells, blood corpuscles, and a wander- 

 ing cell on the edge of the blood space. x245. 



REFERENCE LETTERS. 



-4. 1, lirst Mtitemiji. 

 J. JJ, Nfcoml auteuna. 

 Ah., abdomen. 

 unr., aorta. 



n. i/. S., granulated yidk products. 

 B. C., blood coll. 

 /.'. .V, liloncl space. 

 >'h.. eggshell. 

 cp., carapace. 



J'cy., products of ci-ll ilcgeimration. 

 /.'(/., ectoderm. 

 l : - nd., endoderiii. 



/.?., liber-substance nf uerve cord. 

 ''. /'', ganglion of mandible. 

 yc., ganglion eel], 

 ijf., liber ball ot'Nerinid antenna. 

 U., heart. 

 /<((., bypodermia. 

 hi/., liindgut. 



//., lateral liber-mass of brain. 

 .!/((., mandible. 

 Mrs., meaoblast. 

 ilu., muscle cells. 

 Mu.f., flexor niust-le. 

 Mts., metastoma. 

 ii. c., neural cord. 

 O. G., optic ganglia. 

 f.. optic eulargenient. 

 p. c.. pillars of carapace. 

 p. r., perineurinm. 

 p. s., pericardial sinus. 

 7i'/., retinogen. 

 >7if.. Btomodseum. 

 vac,, vacuole. 

 i/. r., wandering cell. 

 !/. "., yolk nest. 



