1915] Schurtiachcr: On Blcpliarocoriis C'liii sp. nor 99 



That it is a very definite and constant structure is shown (1) by 

 the fact that in no case could a ciliate of this form be found in which 

 it was lacking, (2) by its great rigidity, and (3) by the fact that it 

 is always wound the same wa.y. i.e.. so as to form a right-hand screw. 



In the anterior ventral region of the body there is a deep inpoek- 

 eting resulting in the formation of the vestibule (vest., pi. 13, figs. 

 1. 3, 5) mentioned above. This vestibule extends the entire width of 

 the body. Its lower wall is made up of a ventral lip or mentum (v. I., 

 pi. 13, figs. 1, 2), thickest in the mid-ventral region, thinning out dorso- 

 laterally on each side imtil it reaches almost to the mid-lateral lines 

 and extending about one-fifth of a transdiameter farther posteriorly 

 on the left side than on the right side of the body. 



The dorsal wall of the vestibule is formed by the frontal cap {fr. c, 

 pi. 13. figs. 2. 5), a prolongation of the body anteriorly and dorsally 

 to the mouth {or., pi. 13, figs. 1. 3). It is thickest in the middle and 

 extends laterally on each side to form the dor.so-lateral edges of the 

 ve.stibule. 



Arising in common from the mid-dorsal line of the frontal cap 

 throughout its entire length are two plates, known respectively as the 

 right and left dorsal plates (r. d. pi., I. d. pi., pi. 13, figs. 1, 2), the left 

 one being much the larger of the two. Neither plate lies wholly in 

 one plane. In its anterior part (pi. 13, figs. 1, 2, 5) the left dorsal 

 plate extends laterally and ventrally around the end of the frontal 

 cap and ends at a point just to the right and posterior to the corre- 

 sponding end of the right dorsal plate. The main part of the plate 

 arches away from the body slightly, curves ventrally around the left 

 side of the body and extends along its whole ledge over the left margin 

 of the ventral lip (v. I., pi. 13, figs. 1. 2). thus forming a lateral wall 

 for the vestibule on the left side of the body. Posteriorly, however, 

 its margin does not extend as far back as the posterior lateral edge of 

 the vestibule; there is left in this region consequently an ojiening into 

 the vestibule posterior to the left dorsal plate (pi. 13, fisi. 3 ). 



The right dorsal plate, like the left, extends laterally and ventrally 

 around the end of the frontal cap. The remaining part simply arches 

 away from the body laterally and. unlike the left dorsal plate, bears 

 little relation to the vestibule. 



Situated on the anterior dorsal side of this ciliate and best seen in 

 a dorsal view (pi. 13, fig. 4) is a zone of cilia, the dorsal ciliary zone. 

 These cilia (d. ril., pi. 13, figs. 2, i. 5). wliile not broad enough to Ije 

 called membranelles, are fully as long as tlie adoral memhranelles of 



