47, 



The stomodaeiim is ofte?a attached to the anterior, a;o.d 

 to part of the ventral margins, of the foot, but its posterior 

 end, figure 61, std, lies free between the mantle lobes, some- 

 times almost, if not quite, in contact with the test, sometimes 

 raised well abore it. The anterior end of the midgut is enlarg- 

 ed to form the stomach, which corimunicates with the liver-pouches. 

 Most of the tissue dorsal to the intestine has beer, \ised in form- 

 ing the mantle, which is now separated from it by a large space. 

 This space extends to, and around, the anterior adductor tmiscle 

 anteriorly, and nearly to the margin of the shell posteriorly. 

 The cerebral, pedal, and visceral ganglia, with their c ommis spires , 

 have been formed. The otocysts, figure 61, ot, have apparently 

 been entirely closed off, and each contains an otolith, which 

 stains deeply witli haematoxj'-lin and, a little later, plainly 

 shows concentric structure. 



As the otocysts have nearer been opai to the exter'ior, 

 development having taken place inside a closed test, the otolith's 

 cannot be foreiga particles. 



The only places where the outer test is attached to the 

 body of the embryo lying inside it: are, around the blastopore, 

 the apical plate, and the opening of the unpaired pouch, figure 

 33, r. The embryo still swims rapidly but has periods of rest. 



