9. 



filled with blood an.d disappear when the presfjure is remoA'ed. 

 "When the muscles of the tentacle contract, the blood is forced 

 back, and the blood-space Tnay be completelj obliterated. 



The tentacles that fringe the postero -ventral margins 

 of the mantle, have, beneath their epithelium, both longitudinal 

 and transverse strands of muscle fibers, an.d generally several 

 blood spaces. "iThile branches of the pallial nerves have not been 

 traced into these tentacles, such branches can be traced to their 

 bases, and there can be no doubt that the tentacles are s^ipplied 

 by fibers from these nerves. 



Each tentacle has at least one papilla and frequently 

 there are several papillae upon its surface. In development the 

 tentacle is preceded by a single sense papilla which is carried 

 out by the growth of tlie mantle near its base, into a conspicuous 

 projection. As this projection grovrs, other sorise papillae make 

 their appearance on its sides, and the papilla at its tip may or 

 may not retain its position. In a few cases the tentacles divide 

 or brarich. This is most common witli the tentacles fringing the 

 posterior expansions of the mantle, soon to be described. 



Considering the origin, structure, and inervation of 

 the siphonal tentacle and the marginal tentacles, there can be 



