560 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



E XLIX. 



(Stages X ami XII.) 



FIGS. 169-173. Parts of serial transverse sections through the embryo of Alpheus saulcyi in Stage 

 X. lu Fig. 173 the reproductive organ R. 0. is cut. xl-'J, (Fig. 173, x234.) 



FIG. 174. Horizontal section through nervous system of the first larva, on a level with the u>-sopha- 

 geal commissures. x234. 



FIGS. 175, 176. Transverse sections through the neural cord of the first larva. In Fig. 170 the 

 transverse commissure of the ganglia of the tentli segment is cut and in Fig. 175 

 the short longitudinal commissures between the tenth and eleventh segments are 

 sectioned, x !-") 



REFERENCE LETTERS. 



A.I, first antouua. 

 A. II, .second autenn:i. 

 I//., abdomen. 

 ay., antenna! gland. 

 H.c., Mood corpuscles. 



/)'. A'., blood ,ii nils. 

 /.'c., branchia. 

 </>., ra.ra|iarr. 

 End., endoderui. 

 /</., foregut. 

 (/. '., ganglion cell. 

 Hd., liyiiodermis. 

 //(/., liiiidgiit. 



/./., lateral liber-ina.s.s of brain. 

 Mfl., base of ujaiidilili 1 . 

 Mi's., Miesoderni. 

 My., iiiostMiteron. 

 MIL. niiKscle. 



Mn. ., extensor muscles ol' abdomen. 

 Mn. I., llexor muscles of ali 

 MJ- .. b:i.se of luaxilbr. 

 M.rptl., base of maxillipeds. 

 n. <., neural cord. 

 "/., mitic nber-mass ol luaui. 

 a. if., optic gaugliuu. 

 /'/.. |ierine:iriiiin. 

 /.'. (>., reproductive organ. 

 "<>i/., brain. 



I. c., transverse commissure. 

 .//. c., wandering cells. 



