THE ANATOMY OF ONCHOLAIMUS VULGARIS, BAST. 119 



Alimentary System. 



The alimentary system is divided into pharynx or buccal 

 cavity, oesophagus, intestine, rectum, and cloaca in the male, 

 anal canal in the female. 



The pharynx (PI. 7 , fig. 2, ph .) is cup-shaped, narrowiug 

 at its hinder extremity '085 mm. long, '034 mm. in diameter. 



The mouth is surrounded by the diaphragm-like ring of the 

 lips. In life the lips are in constant motion. 



The cavity of the pharynx is shamrock-shaped in transverse 

 section. It has a cuticular lining', and from this lining there 

 project into it three large teeth (ibid., d.) composed of the 

 same substance, one lying in the dorsal line, the other two 

 subventral. At the tips of these teeth are situated the 

 openings of the oesophageal glands. Outside the cuticle is a 

 fine membrane connected with the cells of the longitudinal 

 lines. 



The oesophagus (PI. 7, fig. 1, oes.) is 1-3 mm. in length. 

 Its general shape is that of an heraldic club. In diameter it 

 measures, at its commencement, "0525 mm., at the level of 

 the nerve-ring the same, and at its broadest part posteriorly 

 •08(32 mm. 



The walls are thick and muscular, the direction of the 

 fibres radial. When at rest the internal surfaces are in 

 apposition and the lumen appears in cross section tri- 

 radiate — one radius in the midventral line, the other two 

 subdorsal. There is a cuticular lining considerably finer 

 than that of the pharynx. 



The organ is essentially a strong suction pump, since the 

 radial muscle-fibres in contracting must open out the lumen 

 with considerable force. This appears a somewhat anomalous 

 organ for a free-living form. 



The oesophageal glands occur in the posterior quarter of 

 the organ, as canals ramifying in the muscular substance. 

 They unite to form the ducts, which run forward and open 

 into the pharynx at the tips of the teeth. 



