DENTALIUM. 227 



points d'appui to turn from side to side, and also to climb 

 and secure its food from the stems of the foraminiferous 

 polyparia ; the third or basal section is a long flattish pedicle, 

 deeply grooved on its upper and lower surfaces, extending to 

 the base of the stomach, into which it opens, as it is hollowed 

 out as far as the tenacular flaps, but there is no passage to 

 the exterior surface. I have failed to discover the reason for 

 this connection with the stomach : the hollow part is filled 

 with water, but from what source does not appear, though I 

 think it must come from the buccal aperture. The use of this 

 singular structure is clearly to augment the flexibility of the 

 foot, as the animal frequently and suddenly doubles it up as 

 the elephant does its trunk ; and also to withdraw the two 

 anterior parts into the hollow portion : this retractile action 

 is necessary in consequence of the peculiar mouth of the ani- 

 mal and the rigid character of the anterior end of the mantle, 

 to convey the sustentation captured by the tenacula into the 

 cavity of the mantle within the reach of the very short folia- 

 ceous cirrhi at the buccal orifice. From the foot an elastic 

 fibrous riband runs, on each side of the body, to the posterior 

 terminus, and affords the animal the power of greatly con- 

 tracting and dilating that end of it, as may be seen by the 

 creases of contraction, which in some degree give the ap- 

 pearance of annulations. 



At the base, and above the pedicle of the foot, if that sur- 

 face of the animal is upwards which lies in the concavity * of 

 the shell, and vice versa, in the convexity, is inserted a distinct 

 light yellow tubular buccal appendage, without eyes or tenta- 

 cula, which can only be considered a kind of external oeso- 

 phagus, and as regards its accessories and form, has no pre- 

 tensions to be styled a head ; it is encircled by about eight or 

 ten short dendroid tentacular strands ; its cavity forms two 

 extremely dilatable pouches divided by a longitudinal septum, 

 which become compressed and merge apparently into one at 

 the point of passage into the stomach. These external re- 

 ceptacles invariably contain from ten to forty, or even more, 



* Concavity is dorsal, convexity is ventral. M. Deshayes states the 

 contrary, but he is mistaken. 



Q2 



