600 W. S. NICKERSON, 



oral end is not specially modified in any way. Its lumen is com- 

 pressed laterally and nieasures in transverse section about 5 X 37 ^it, 

 Its wall consists of a thin cuticula outside of which is a layer of 

 delicate longitudinal muscle fibres. Circular fibres are lacking. Im- 

 mediately around the prepharynx (Fig. 8) is a cord of parenchyma in 

 which no muscle fibres are present. This has an elliptical outline 

 in cross-section and extends longitudinally through the central portion 

 of the neck. The strong dorsoventral fibres of the neck musculature 

 border this parenchyma on the sides and probably by their contraction 

 produce the lateral compression which closes the lumen of the pre- 

 pharynx. At its hinder end the prepharynx enlarges abruptly to 

 unite with the pharynx. This latter organ is nearly cylindrical in 

 form and measures about 0,45—0,55 mm in length. It is however 

 laterally compressed giving an elliptical outline in transverse section 

 measuriug about 0,26 X 0,315 mm. Its narrow lumen measures only 

 about 20 fi transversely by 212 f.i dorsoventrally. It is situated above 

 and a little in front of the sexual aperture (Fig. 7). 



The intestine extends from the pharynx back to the region of 

 dorsal flexure of the body. Its shape undergoes certain changes of 

 outline as seen in transverse section but I have no means of know- 

 ing to what extent these changes are due to temporary states of 

 contraction. Figs. A 1 — 9 show in outline the form and relative size 

 of the intestine at 9 successive points back of the pharynx the last 

 being taken opposite the ovary. Posterior to the ovary the intestine 

 undergoes very little change in size or shape to its abruptly rounded 

 termination. Monticelli divides the digestive tract back of the 

 pharynx in C. michaelis into two regions Oesophagus and intestine. 

 I See no reason for making a similar division in this case as there 

 is no characteristic structural ditierence between the two parts nor 

 any definite line of Separation. I do not see that anything would be 

 gained by making such a division arbitrarily. 



The epithelial lining of the intestine is composed of a Single 

 layer of cells which show great Variation in form evidently due to 

 amoeboid changes. In some regions they appear flattened almost 

 squamous in character in others as greatly elongated cells with their 

 nuclei near the base and with their outer ends projecting into the 

 lumen of the intestine and vacuolated. The epitheliuni rests upon a 

 delicate basement membrane beneath which is a layer of longitudinal 

 muscle fibres. The outer layer of circular fibres described by Monti- 

 celli as occurriug in C. michaelis is represeuted in C. occidentalis 



