296 GRIFFIN. 



by . them. In this space lie several oblique rows of fine cilia which 

 l^robably are homologous with the endoral cilia of other Hypotricha. 

 (See text figures 5 and 6; Plate I, figure 1.) At the oral aperture three 

 or four of these rows (occasionally more) lie side by side, forming a 

 ciliated band which extends from the mouth to the inner end of the 

 pharynx, narrowing slightly as it passes inward. These cilia are the 

 most difficult feature of the ciliation to observe in the living animal, but 

 with favorable specimens and using high powers of magnification the 

 lines of vibrating organs can be seen. However, I could not be sure 

 of the observation nor of the nature of the organs without recourse to 

 sections, which showed the cilia and their arrangement with sufficient 

 clearness. (See text figures 5 and 6.) The ends of the rows of endoral 

 cilia may extend upon the anterior wall of the pharj'nx. (See text 

 figure 6.) 



I have since found the suboral group of membranellse and the endoral 

 cilia in another unidentified species of Euplotes, and therefore venture to 

 suggest the possibility that these structures may be found in still other 

 species of the genus. The praeoral cilia of E. liarpa described by Wal- 

 lengren are different in position and aiTangement from both the suboral 

 membranellffi and the endoral cilia of B. worcesteri. They ma.y, however, 

 be homologous to. the endoral cilia. 



The extreme shortness of the pharynx is a noticeable feature in most 

 of the Hypotricha. The organ reaches its greatest development in the 

 Euplotida?, especially in the genus Euplotes. The pharynx of Euplotes 

 worcesteri is longer than that of any other Euplotes known; however, 

 that of E. vannus is only slightly shorter. In other species of the genus 

 the length of the pharynx is much less. The forward curvature of the 

 pharynx of E. ivorcesteri and E. vannus also is remarkable among 

 Hypotricha. 



The adoral and pharyngeal membranells and the endoral cilia are in 

 nearly constant motion. In addition to gathering food particles the 

 anterior adoral membranellas appear to be the principal natatory organs 

 of the animal. The suboral membranella3, on the contrary, are apt to be 

 found at rest except when food is being swallowed. These membranellffi 

 appear to be triangular. The small area covered by them is oval in 

 outline, its axis obliquely inclined to the ventral edge of the oval aperture. 

 The tips of the outermost menibranellge project slightly from the mouth, 

 and just clear the tips of the adoral membranellffi. Direct observation, 

 many times repeated, has proved that food iDarticles which arrive at the 

 mouth are seized between the adoral membranellse above and the suboral 

 below, and forced into the pharynx. 



That the thrusting power of the two sets of membranellEe is consider- 

 able was shown one day when I observed a Euplotes which had captured 

 and was trying to swallow a small Lembus rather more than one-half as 



