BRYOZOA, WITH DESCRIPTIONS OF NEW SPECIES. 375 
canal is highly irritable, particularly the esophagus and stomach, 
in the walls of both of which, minute, transverse striz are dis- 
tinctly visible, probably indicating the presence of muscles. The 
stomach is perpetually in motion when the animal is displayed, 
contracting in an undulating or vermicular manner from above 
downwards. The contractions of the esophagus, too, are very 
decided on receiving food, which for a second or two rests in the 
enlargement, and is then hurried into the stomach with great 
rapidity. 
The alimentary canal of Plumatella and Alcyonella does not 
vary in any important manner from that of /redericella. In the 
two former, however, both the csophagus and stomach are 
shorter than they are in the latter genus. 
In all these genera no disturbance of the parts of the aliment- 
ary canal takes place on the retraction of the polype : the animal 
sinks into the cell with the csophagus, stomach and intestine 
erect as they were when the tentacles were exserted and in full 
play. Not so, however, in Paludicella, Pl. V, fig. 2; in this 
genus the alimentary canal is doubled upon itself when the 
polype 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 cesophagus, 
fig. 1 h, is observed to be long and slender, and to have a dis- 
tinct 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 f. 
The stomach, fig. 1 2, is rather short, considerably enlarged above 
and tapering to the inferior extremity, where it 1s rounded : the 
walls are thick, and apparently filled with yellowish brown 
coloured granules, probably hepatic as in the marine species. 
The intestine, 7, arises from the superior extremity close behind 
and a little above the cardia. The pyloric opening is well de- 
fined and circular; soon after its origin the intestine is sud- 
denly enlarged, forming an oval swelling, &, in which the feces 
may be seen collecting ; it contracts above this swelling, and 
continues afterwards for nearly its whole length of equal diame- 
