11. 



Ihetlier the stirmiUis is transmitted through, the siphonal tentacle 

 or not, has not been determined, but its position, coiled on the 

 surface of the mud, suggests the possibility. 



All of the er-cperiinents that were tried to determine the 

 function of the tentacle resulted in failure, inasmuch as specimens 

 in Tffoich the tentacle Zaad been removed, seemed to be as sensitive 

 to jars as uninjured specimens. It may be remarked, however, 

 that the Jars of a small vessel, can. at best bear only a slight 

 resemblance to Jars af.fecting the surface of the mud on the bot- 

 tom of the ocean, such as would be caused, for instance, by the 

 swimming of a floundei'. 

 Posterior expansions of the mant 1 e , - 



These e:<pansions, figures 1, 3 and 10, pe., lie oppo- 

 site the extremities of the posterior shell stripes. They con- 

 sist of flat, somewhat triangular extensions of the edges of 

 the mantle. The anterior border of each is fringed with ten- 

 tacles, resembling the ordinary marginal tentacles, but more 

 frequently branched, and usually tiiey have a rather larger pro- 

 portion of sense-papillae. Tlae inner surfaces of the expansions 

 are very densely ciliated. Near the base of eao.l\ is a fold or 

 ridge, along the side of -vtxich such dirt as gains access to the 



mantle chamber is swept. This dirt is swept back over the ex- 



