1 68 WILSON. [VOL. I. 



free end moves about in every direction and carefully searches 

 the surface around the opening. Having found a particle of 

 food, the edges are rolled in ventrally toward each other, if not 

 already in that position, and form a more or less closed tube. 

 The whole ventral surface (which is now the interior of the 

 tube) being ciliated, there is generated a current which quickly 

 carries the food toward the mouth. The proboscis often 

 assumes a similar tubular shape when it is not elongated, as 

 can be seen in Fig. 2, so that the curling inward of the edges 

 is independent of the strong contraction of the circulat muscles 

 which produces the extension. 



Often also it rolls itself into a tight coil, commencing at the 

 tip and curling over ventrally as though it were grasping some 

 object, but nothing save a few food particles is to be found in 

 it, which are much too small to occasion any such effort. 



The proboscis is very sensitive over its entire surface, but 

 especially so on the ciliated ventral portion, and the slightest 

 irritation there results in a quick withdrawal. 



As would be inferred, such an appendage is of extreme im- 

 portance to the animal, and yet it breaks off upon the slightest 

 provocation. Whether such a separation is necessarily fatal or 

 not, and whether the animal possesses the power of regenerat- 

 ing its proboscis, could not be definitely determined. 



It hardly seems probable, however, that the animal could live 

 for any length of time without it. But it was found that the 

 proboscis itself was so highly innervated that it retained its 

 vitality, and to a marked degree its sensitiveness also, for a 

 long time after separation, a week or more if kept in fr^sh sea 

 water. When the tide goes out, though there is always water 

 left in the burrow, the proboscis is withdrawn and all indica- 

 tions point to the conclusion that the animal retreats to the 

 lower part of its burrow. 



Like other gephyreans, this species secretes a thick mucus, 

 which lines the burrow walls and penetrates the mud for some 

 distance, giving it greater firmness and solidity. 



This mucus, as in so many other cases, oxidizes the iron in 

 the mud, so that the walls of the burrow are a rusty brown 

 color and stand out in sharp" contrast to the surrounding black. 



