THE GUT OF NEBALIACEA S 



to the regular row of setae (gs.i). Of equivalent functional significance is the grinding organ formed 

 by the setae alone (g.s.i), which slope diagonally backwards and outwards almost parallel to, and 

 rubbing against, a slightly setose horizontal shelf of each lateral wall. The more anterior of these 

 grinding setae are longer than the posterior ones, their tips curve upwards and a pair of small ridges 

 (d.r.') lie medial to the basal thickening on which they are inserted. 



a.m 



oes 



mo. 



Fig. 2. Diagram of the right half of the fore-gut of Nebaliella extrema. A, region at which Fig. 3 A was cut; B, region at 

 which Fig. 3 B was cut. a.m.p. anterior median projection; d.ca. dorsal caecum; d.gl. digestive glands; d.gl.o. opening of the 

 digestive glands; d.p. dorsal process; d.r. dorsal ridge; d.r.' small ridge on the dorsal ridge; ^.^.j strong setae; ^.y., short stiff 

 spines; i. intestine; l.p. lateral pad; m. mandible; mo. mouth; yn.p. median pad; oes. oesophagus;/), long projections; v.p.ch. 

 ventral pyloric chamber with opening of the digestive glands ; outUne of the lumen of the gut laterally. 



Ventral to the row of spines {g.s.2) is a slight ridge on each lateral wall behind which is a strong 

 contractor muscle. This ridge marks the division between the oesophagus and the stomach. 



There is no distinct division into cardiac and pyloric regions, but, posteriorly, where the spines 

 ig.s.i) and setae {g.s.i) cease, the lateral walls approach one another more closely and their surfaces 



