178 Mr. A. Hancock on the Anatomy of the 



two former, however, both the oesophagus and stomach are shorter 

 than they are in the latter genus. 



In all these genera no disturbance of the parts of the alimen- 

 tary canal takes place on the retraction of the polype : the ani- 

 mal sinks into the cell with the oesophagus, stomach and intes- 

 tine erect as they were when the tentacles were exserted and in 

 full play. Not so however in Paludicella, PI. IV. fig. .2 ; in this 

 genus the alimentary canal is doubled upon itself when the po- 

 lype is retracted ; and moreover the parts are somewhat modified, 

 approximating this form more closely to that of the marine 

 species. 



When the animal of Paludicella is protruded, the oesophagus, 

 fig. 1 h, is observed to be long and slender, and to have a di- 

 stinct pharyngeal dilatation at the commencement, where vibra- 

 tile cilia can be seen in vigorous action. It communicates with 

 the upper extremity of the stomach by a circular orifice, fig. 2/. 

 The stomach, fig. 1 i, is rather short, considerably enlarged above 

 and tapering to the inferior extremity, where it is rounded : the 

 walls are thick, and apparently filled with yellowish brown co- 

 loured granules, probably hepatic as in the marine species. The 

 intestine, J*, arises from the superior extremity close behind and 

 a little above the cardia. The pyloric opening is well defined and 

 circular ; soon after its origin the intestine is suddenly enlarged, 

 forming an oval swelling, /:, in which the faeces may be seen col- 

 lecting ; it contracts above this swelling, and continues afterwards 

 for nearly its whole length of equal diameter ; it passes upwards 

 in a straight line parallel with the oesophagus, but unattached to 

 it, and terminates in a rounded anal extremity, Z, immediately 

 below the base of the tentacles where it perforates the tentacular 

 sheath. The upper end of the stomach, close to the pyloric ori- 

 fice, is furnished with vibratile cilia, and here the alimentary 

 matters may be seen rapidly rotating by their influence. The 

 faeces are formed into small pellets, which, coming from the en- 

 larged portion, pass up the intestine and are expelled at the 

 anal orifice. The whole of the canal is as highly irritable as in 

 the other species ; the stomach undulating from above downwards 

 in the same manner, and the oesophagus is equally expert in 

 transmitting food to the stomach. But neither in Paludicella 

 nor in the species before alluded to does the pharyngeal swelling 

 exhibit in any marked manner the sudden puffings and contrac- 

 tions so conspicuous in the marine species, and noticed originally 

 by Dr. Farre. 



On retraction of the polype, the alimentary canal of Paludicella 

 is doubled upon itself in much the same way as in Boiverbankia. 

 The basal disc of the tentacles is then brought down as far as 



