THE GUT OF NEBALIACEA 



n 



instead of ventrally. A small ventro-lateral dilator muscle {v.l.dil), three small muscles (a.s.m.) 

 extending anteriorly and a muscle (p.m.) pulling posteriorly from a triple insertion on the gut were 

 found. The anterior muscles (a.m. and a.h.m.) are small but correspond to similar muscles in Nebalia. 

 The digestive sac has dorsally and ventrally a pair of longitudinal muscle bands. Small segmental 

 muscles which support the thoracic limbs lie in the wall of the sac and cause slight ridges in it. No 

 musculature was found on the intestine and only a small sphincter at the anus {a.sp.). 



Fig. 7. Diagrams of the right halves of A, Nehaliopsis, B, Nebalia, and C, Nebaliella, showing the position of the gut in the 

 body cavity of each. (The positions only of the limbs are indicated in B and C.) a. anus; a.ch. anal chamber; a.sp. anal 

 sphincter; d.gl. digestive glands; d.p. dorsal process projecting down the intestine; d.s. digestive sac;/.^. fore-gut; i. intestine; 

 m. mouth ; md. mandible ; r. rectum ; r.ca. rectal caecum ; sep. septum. 



THE STRUCTURE OF THE GUT OF PARANEBALIA LONGIPES 



(Wilemoes Suhm) 



No specimens of Paranebalia were available for examination. Nevertheless, to complete the survey 

 of the Nebaliacea Thiele's description may be quoted. He found that the gut is, on the whole, like 

 that of Nebalia, but records these differences: (i) strong spines are present under the long setae on 

 the ventral side of the ' hypopharynx ' (the ventral lip) ; (2) the rows of setae on the dorsal ridge in the 

 pyloric region do not extend far back, and the funnel formed by the dorsal process bears no setae ; 

 (3) two ventral bristle plates take the place of the small lateral ridges {l.r.) of Nebalia. These plates 

 are composed of a transverse row of thick setae which meet each other across the lumen of the gut. 

 The midmost setae are longest. 



Thiele's diagram does not show an anterior median projection, lateral plate setae (but he has depicted 

 the left side), setae on the walls of the oesophagus or cardiac region, or a ventral cardio-pyloric valve. 



