THE ANATOMY OF SCALIBREGMA INFLATUM. 257 



ing attention to tlie nature and probable functions of the 

 oesophageal pouches, and to some details of the structure of 

 other parts of the digestive tract, e. g. he observed the 

 ciliated epithelium lining the oesophagus, Wiren (1887, pp. 

 30, 37) referred to some points in the histology of the oeso- 

 phagus and stomach. 



The mouth (fig. 2) is a transverse slit, situated ventrally 

 between the peristomial and the first chtetigerous segments, 

 through which the smooth, spherical, eversible pharynx or 

 " proboscis " may be extruded. The mouth is bordered in 

 front and behind by papilliform elevations of the skin. The 

 pharynx, when fully protruded, is a smooth, globular structure, 

 not provided with spines or any other armature. When it is 

 withdrawn the anterior part of the alimentary canal — the 

 part lying in front of the first diaphragm — forms a spherical 

 mass, from which muscle strands pass to the neighbouring 

 body-wall (fig. 14). 



The oesophagus is a narrow cylindrical tube about 8 — 9 

 mm. long (in the specimen 56 mm. long), bearing just in 

 front of the fourth diaphragm a pair of hollow glandular 

 pouches, which in this specimen are about 2 mm. long and 

 1'8 mm. wide. Each is a somewhat heart-shaped sac, at- 

 tached to the wall of the oesophagus by its apex, its free 

 wider end being bi- or tri-lobed. The two pouches are 

 united in the middle line, either directly or by a small median 

 sac, into which both lateral pouches open. They discharge 

 their secretion into the oesophagus through a small duct 

 leading from the median sac. 



About the level of the sixth to eighth seta3 the oesophagus 

 passes somewhat suddenly into the much wider stomach, 

 which even in spirit specimens still bears traces of the 

 bright orange-yellow colour which Danielssen noticed in 

 fresh specimens. In all the specimens examined the walls of 

 the stomach are folded, but whether these folds are natural 

 it is impossible to state with certainty. The walls of the 

 stomach and intestine are marked by a number of parallel 

 lines which pass round the tube from the ventral side to th^ 



