100 University of California Publications in Zoology [Vol. 16 



the ventral lip. Seen in .side view (pi. 13, fig.s. 1, 3, 5). they appear 

 to arise from the entire dorsal surface of the dorsal plates. This 

 impression is .still further strengthened while observing the living 

 animals, for the cilia then part to the sides of the anterior process and 

 hang down over each .side. That they do not arise in such a manner 

 is, however, clearly shown in a dorsal view. Here they are seen to 

 take their origin in a gradual curve, ccmvex anteriorly, extending from 

 the middle of the dorsal surface of the left dorsal plate to the extreme 

 right side of the body. 



On the ventral side of the ventral lip [v. I., pi. 13, fig. 2). extending 

 obliquely from the extreme anterior mid-ventral point to the point 

 where the lip meets the left side of the body and then passing over 

 its margin ,iust to the edge of the vestibule, is a row of adoral menibra- 

 nelles {ador. m., pi. 13, figs. 2, 5). The longest of these membranelle.s 

 is a little less than one-fourth of a transdiameter of the whole body. 

 Their free ends point anteriorly and ventrally in the fixed material. 



The mouth or oral opening {or., pi. 13, figs. 1, 3) is an irregular, 

 poorl.y defined opening leading directly into the oesophagus. It is 

 situated at the left posterior end of the vestibule close to the ventral 

 side of the body. 



The oesophagus (oes.. pi. 13. figs. 1, 3, 5) lies in an oblifjue position 

 with reference to the long axis of the body, its anterior end connecting 

 directly with the oral opening in the left ventral part of the body, its 

 posterior end dorsal and on the right side of the body. The right wall 

 of the anterior one-half of the oesophagus forms a concavity in the 

 endoplasm. around which fits the left wall of the macronucleus. The 

 posterior end, beginning at a point about seven-eighths of its length 

 from the anterior end, bends sharply to the ventral side. The oeso- 

 phagus is essentially round in cross-section and at its anterior end is 

 about one-sixth of a transdiameter wide. The lumen gradually nar- 

 rows as the posterior end is approached and disappears at a point in 

 the endoplasm approximately midway between the macronucleus and 

 the posterior end of the body. The oesophagus is ciliated along its 

 dorsal wall with fine cilia, increasing in size and continuous anteriorly 

 with the oral membranelles. 



The oral membranelles (or. ni.. pi. 13, figs. 1. 5) are .small blade- 

 like .structures, the longest being about one-half the length of an adoral 

 membranelle. They arise in a line from the dorsal wall of the vesti- 

 bule .just anterior to the oral opening. Posteriorly they decrease in 

 length and are continuous with the cilia of the oe.sophagus. 



