TILE DEVELOPMENT OF ASTERINA GIBBOSA. 409 
Fig. 117. Section from star-fish, in which R equals 2°2 millimetres, 
showing the continuity of rachis and ovoid gland, and that the rachis 
now extends in both directions. Magnified 150 diameters. 
Fig. 118. Section from star-fish, in which R equals 3 millimetres, show- 
ing fully developed ovoid gland and changed form of stone-canal. 
Magnified 350 diameters. 
PLATE 26. 
Fics. 119—121.—Portions of three sections from the same series as Fig. 
118. Fig. 119 shows the genital rachis enclosed in the branch from the 
aboral sinus, ad. Fig. 120 shows the passage of the genital rachis into the 
rudimentary genital organ, and the outgrowth of septum which cuts off the 
perihemal space surrounding this rudiment from the “ genital vessel.” ad. A 
branch of the aboral ring. Fig. 121 shows the development of the cavity of 
the genital organ. Magnification 350 diameters. 
Fies. 122 and 123.—Two sections of young ovaries, from a specimen in 
which R equals 3°7 millimetres. Fig. 122 shows the continuity of the ovary 
and rachis, Fig. 123 the outgrowth of germ cells to form the genital duct. 
Fic. 124.—Portion of body-wall of gastrula figured in Plate 19, fig. 21. 
Notice the absence of mesenchyme. ezd. Endoderm. Magnification 600 
diameters. 
Fic. 125.—Similar view of the body-wall of slightly older embryo, to show 
the formation of mesenchyme. Same magnification. 
Fic. 126.—Portion of the gut epithelium of larva figured in Plate 20, 
figs. 51—53. Same magnification. 
Fic. 127.—Epithelium of the adult cesophagus of the larva shown in 
Plate 22, fig. 76, Stage G. Magnified 480 diameters. 
Fic. 128.—Epithelium of the pyloric sac (larval stomach), from the same 
section as foregoing. 
Fie. 129.—Epithelium of the lateral wall of the stomach of a star-fish, in 
which R equals -8 millimetre. Magnified 480 diameters. 
Fie. 1380.—Epithelium of aboral wall of the stomach from the same section 
as foregoing. At X it passes into the epithelium of the pyloric sac. 
Fies. 131 and 132.—Epithelium of the pyloric sac and of the rectal cecum 
respectively. From the same section as fig. 130. 
PLATE 27. 
Fries. 133—135.—Three sections of the ectoderm of the anterior surface 
of preoral lobe of larva of Stage D. Fix. Disc for fixation. 7. o, Larva 
organ. serv. darv. Larval nervous tissue. Fig. 133 is through the dorsal part 
of preoral lobe; Fig. 135 through its ventral tip. Magnified 480 diameters, 
