THE GUT OF NEBALIACEA y 



is almost circular, the cells are very dense and closely packed together, and some are elongated and 

 project as ridges into the lumen. 



As in Nebalia the intestine and digestive glands are embedded together in a loose tissue of highly 

 vacuolated cells. 



There is a very much reduced rectal gland and an anal chamber comparable to these structures 

 in Nebalia. 



^■h.-^ 



a.m. 



I 



n 



n 



Fig. 4. Diagrammatic reconstruction of the right half of the fore-gut of Nebaliopsis typica in three sections (I-III). a.h. anterior 

 horn; a.m.p. anterior median projection; d.r. dorsal ridge; gl.r. glandular region; /. labrum; l.th. lateral thickenings; pa. 

 paragnaths ; pl.w. plated walls. 



MUSCULATURE 

 The similarities between the musculature of the fore-gut of Nebaliella and that of Nebalia are very 

 striking, as the diagrams (Figs. 6 A, B) show. Differences are that the lateral dilator muscles {l.dil.) 

 of the oesophagus have five points of insertion as compared with two in Nebalia. The muscle corre- 

 sponding to the small median projection muscle is greatly enlarged. The anterior dorsal dilators 

 (a.d.dil.) are also enlarged but the posterior dorsal dilators (p.d.dil.) are reduced, though there is a 

 great thickening of the chitin at their point of insertion. The strong circular muscle (cont.) which is 

 so conspicuous in Nebalia is present in Nebaliella also, though slightly reduced. No muscles could 

 be found in the groove between the anterior horns of the stomach where Nebalia has a few thin 

 strands of fibres. 



