ON THE DIPLOCHORDA. 487 
its way back except along the lateral grooves and out at the 
sides of the mouth. 
Intermittently the end of the pharynx cpens, and the 
particles are shot into the capacious stomach in a scattered 
heap. 
The stomach (sé.) is a large globe with rather thin walls. 
Just ventral to the pharynx is the peculiar thickened gastric 
pad or dise (g.p.), which is strongly ciliated. I have not yet 
determined the exact function of this pad, but it is appa- 
rently concerned with the introduction of particles into the 
stomach, and may possibly assist in the production of the 
food currents. At the posterior end of the stomach a central 
aperture leads into the intestine. Usually this is closed, and 
from its closed edges there projects a long brush of cilia. 
These are usually in very active motion. ‘Their resultant 
effect is to drive a column of water with its particles up the 
centre of the stomach towards the anterior end; here the 
current spreads down the walls of the stomach on all sides 
till it reaches the posterior end, when it again converges 
inwards to form the centre column (Fig. 14). 
hese movements appear to be very characteristic and show 
little variation. They continue without intermission for any 
period from half an hour to two hours, or more. 
Running the length of the stomach, in a ventro-lateral 
position, is a pair of thickened areas (lig. 4) which appear 
to be identical in structure and function with the “ digestive 
> which I have described in Actinotrocha.! Similar 
areas’ 
areas are indicated in a cross-section of Tornaria by Morgan, 
but no reference to them is made in the text. ‘his forms 
one of many smaller anatomical resemblances which confront 
at every turn any investigator of the two types. 
Sooner or later the currents slow down, and the food- 
particles collect at the posterior end. The posterior wall of 
the stomach and the anterior wall of the intestine are pressed 
close together to form a sort of diaphragm which is seen to 
open from the centre like an iris till a large and gaping com- 
1 * Quart. Journ. Mier. Sci.,’ vol. xl. 
