556 MEMoms OF the national academy of sciences. 



Plate XLVII. 



(Stage IX.) 



Figs. 154, 155. Transverse sections tbrougii eutire embrjo of Alpheus saulcyi. In Fig. 154 a yolk 

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



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

 154. x245. 



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

 ing endodernial 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. 158. Sketch of egg embryo, Alpheus saulcyi, of same phase as that represented by Fig. 157. 

 X61. 



Fig. 159. Horizontal section through brain and eyestalks of a slightly older embryo. x<»l. 



Fig. 160. Part of transverse section of similar embryo on level with the mandibles. x245. 



Fig. Ifil. Superficial 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. 



A. I, tirat auteuua. 



A. II, Becoud auteuoa. 

 Ab., alxlomen. 



aor., aorta. 



u.y. S., grauulated yi>lk j)riHliicts. 



B. C, blood cell. 

 B. S., l)lood spaci'. 

 CVi., ejigsliell. 

 c/*., carapace. 



Deg., products <it cell il< -generation. 

 Ac/., ectodcrni. 

 End., cudoderm. 



fa., fiber-substance of nerve cord. 

 G. IV, ganglion of mandible. 

 gc, ganglion cell. 

 <//., fiber ball of second auteuua. 

 U., heart. 

 hd., hypodermis. 

 hg., hiudgut. 



If., lateral liber-mass of brain. 

 J/(t., inaudible. 

 J/fs., mesoblast. 

 Mil., muscle cells. 

 Mu.f., flexor muscle. 

 Uta., metastoma. 

 n. c, neural cord. 

 0. G., optic ganglia. 

 I'/., optic enlargement. 

 p. c, pillars of carapace. 

 ji. r., perineurium. 

 p. s., pericardial sinus. 

 Rt., retinogen. 

 Sid., stomod;»>uin. 

 )>ac., vacuole. 

 y.c, wandering cell. 

 y. «., yolk nest. 



