TBRBBBLLID^E. 



93 



containing contractile fibres, leaves the lower edge of the gut, and widening, is attached 

 with the oblique muscle at the upper and outer angle of each nerve-area. In the space 

 between the bands is the ventral vessel. Under the gut on each side is a large sub- 

 intestinal. The oblique muscles have a tendency to pull the lateral wall and make the 

 ventral wall on each side project as a rounded ridge with a deep median depression, and 



Fig. 148. — Transverse section of the anterior region of Leprsea lapidaria. The oblique muscles, om., 

 cause an indentation on each side. The lower folds of the intestine are prominent. The ccelomic 

 cavity is distended with sperms (spm.) j other letters as Ibefore. 



having in ripe examples the reproductive elements in the interior and laterally the ridge 

 of hooks. At the bottom of the median groove is a ridge in the preparations containing 

 the nerve-area, which is cone-shaped, broad above and pointed below. It lies 

 outside the circular muscular coat and is covered by neurilemma, hypoderm and 

 cuticle. The alimentary canal shows ventrally two prominent folds like a typhlosole. 



VYYV, 



Fig. 149. — Transverse section of the anterior body- wall of Polycirrus aurantiacus, Grube, in the line of the feet. 



Letters as before. 



The hypoderm in the anterior region of Polycirrus aurantiacus (Fig. 149) is largely 

 developed, especially ventrally, and crowded with glands, this layer in the preparations 

 being often thrown into foliate masses apparently from its softness. A strong circular 

 muscular layer occurs within the basement-membrane. The oblique muscles are con- 



