282 



CEPHALOPODA. 



a later stage, the rudiment of the radular sac is added (Figs. 132 and 

 1 33, /•), and a tubular depression, the rudiment of the anterior salivary 

 glands, appears farther forward. 



nua. 



«e 



t.~- 



nicl. 



dt. 



— vt. 



£&.■-- 



FlG. 132. — Sagittal sections through embryos of Loligo vulgaris at various stages, some- 

 what diagrammatic (original). B, section through the region of the mouth. <>,, anal 

 region ; ar, arm-rudiment ; c, cerebral commissure ; eg, cerebral ganglion ; </, yolk ; 

 i/r, yolk-epithelium; i-r/, ectoderm; in. mouth; ma, edge of mantle; ///(/, ehtermi ; 

 mi's, mesoderm (indicated diagrammatically) ; r. radular sac; sd, shell-gland; sp, 

 salivary gland ; tb, ink-sac ; vd, stomodaeum. 



We may here summarise the development of the stomodaeum according to 

 the numerous and careful investigations of Gbenacher, Bobretzky, Ussow, 

 Watase, Joubin, as iollows. The rudiments of the salivary glands very soon 

 divide into two branches assuming in this respect the final form of the adult 



