424 On the Anatomy and Physiology of Trichodina pediculus. 
(fig. 10, cv). The peristome is particularly noticeable as a dis- 
tinct border (d*) along the edge of the inclined plane (c*), and 
for its disappearance at the left side of the mouth (m). The 
pseudo-vestibular lash (e) or tips of the vibrating cilia raised 
above the position which they usually occupy, and in the attitude 
assumed during the expulsion of the feeces. The velum (f, f) is 
only partially expanded. From the position of the animal, the 
basal cilia (g) are exposed at full length. The hooks and radii 
of the adherent apparatus (/) are but dimly seen through the 
corrugated walls of the body. From its peculiar position in this 
view, the vestibule is seen through the open mouth (m). The 
moniliform nucleus (n) is seen in the extreme distance; its 
right (7) and left ends are foreshortened, and appear as two very 
conspicuous, dark-yellow, oval spots, easily seen even with a low 
magnifying-power. 650 diam. 
Fig. 13. An end view of the anterior face, looking directly into the cupu- 
liform disk (c#), and through its walls upon the various organs. 
The ventral region corresponds to the lower side of the figure. 
The anus (a) appears as a faint slit on the right border of the 
vestibule (v). The vibratory crown (b) commences abruptly on 
the right (5!) side, and appears clearly defined as a spiral just 
within the peristome (d!), and equally well marked where it forms 
a curve (4?) at the bottom of the vestibule (v). It is quite evi- 
dent, from this view, that the disk (c*) is inseparable from the 
peristome (d!), except by the slight, narrow furrow from which 
the cilia arise. The peristome is designated by a double border 
(d') (the outer and imner walls) along the spiral course of the 
vibratory row (0, b'); but at the mouth (at d) of the vestibule (v) 
it loses that character, and gradually shades off (at d*) into the 
surrounding surface. The lumen of the vibrating row of cilia— 
the vestibular lash (e) falsely so called—appears distinct from 
this point of view. The contractile vesicle (cv) is in full diastole. 
Its distance from the ventral side of the body is rendered appa- 
rently unusual by the expanse of the disk (c?). The circle (h, h’) 
of hooks and the radii are in the extreme distance, the hooks 
partially overlain by the knotted nucleus (n,') and the cesopha- 
gus (0). The cesophagus (0) is in a scarcely expanded state, 
having but a few granules within it. The principal feature is its 
decidedly marked curve in the opposite direction to that of the 
vestibule (v). The “ digestive vacuoles” (q, q) lie nearest the 
observer. 650 diam. 
Fig. 14. A dorsal view of the body. The leotropic leaning of the cilia (0) 
of the vibratory crown is more decidedly marked than in the 
previous figures. The bottom (c) and flank (c’) of the cup-shaped 
disk are seen in strict profile through the corrugations (r) and 
furrows of the outer (p) and inner (p') walls. The contractile 
vesicle (cv) is in the extreme distance, at its full diastole. The 
peristome (d') appears as a distinct ridge just exterior to the 
vibratory crown. The velum(f) is in a semi-expanded state. 
The cilia (g) of the basal crown are stretched to their full length. 
The circle () of hooks is scarcely recognizable as such in an 
edge view like this. The nucleus (m) lies next the observer. 
The outer wall (p), as in previous figures, bristles with numerous 
immobile, short cilia. The inner wall (p') is dotted everywhere 
by a minute scattered granulation. The longitudinal ridges (7) 
of the body bear a singular resemblance to muscles. 650 diam. 
