Physiology of Trichodina pediculus. 421 
vestibule (v) and cesophagus (0), being seen as it were edgewise, 
is foreshortened upon a flat surface. The lettering is the same 
as that used for the figures of the plates. 
b GH Clas c ch 
| ARETE GaN Ry FAG THEY WORT BMT HR 
| 7 
Gan: SDD 
EEN 
PINS 
\ YY 
EXPLANATION OF THE PLATES. 
The corresponding parts in all the figures of the plate and the wood- 
cut are lettered alike as follows :—a, anus; 0, vibratory crown; 51, begin- 
ning of the vibratory crown; 67, end of the vibratory ‘crown within the 
vestibule ; 5°, furrow of the vibratory crown; c¢, the bottom of the cupuli- 
form disk; c', the side of the disk; c?, the side of the disk rolled back ; 
c*, a front view of the disk; c‘4, the “inclined plane” which lies upon the 
cornice-like oblique projection below the aperture of the vestibule ; cv, the 
contractile vesicle; d, the peristome opposite the vestibular aperture ; 
d‘, the dorsal region of the peristome; d’, the inrolled edge of the peri- 
stome ; d*, the peristome at the edge of the inclined plane (c*); d‘, the 
peristome where it becomes blended with the general surface of the body ; 
d°, the first turn or ventral region of the peristome; e, the lumen of the 
edge of the row of vibrating cilia, hitherto supposed to be a distinct vesti- 
bular lash (“ bristle’); f, the profile of the velum; f, the free edge of the 
velum; f*, the basal edge or line of attachment of the velum; g, the basal 
