NEW PERITRICHOUS INFUSORIAN. 245 
disc turned forwards. It can now be seen to have, attached 
to one surface of its disc, a somewhat flattened and roundish 
mass of protoplasm,—the body,—in which are lodged pharynx, 
vacuoles, and nucleus, the mouth being situated in the body 
at its junction with the disc. The animal may therefore be 
conveniently described under the heads of (1) the disc and 
(2) the body. 
l. The disc is of a very complex structure, presenting us 
with a central depression surrounded by the hooked ring, 
striated border with the fringe of motor cilia, while on its 
oral side a few long and slender setz (s., fig. 2) are attached. 
The motor cilia (c., figs. 1, 2,6) are arranged in a com- 
plete circle on the margin of the striated border. They are 
stoutish, nearly of the same size from base to apex, and 
of a pale green colour, continuously in motion, undulations 
running round the disc even when the animal is stationary. 
They have on the oral surface and close to their bases a 
small nodule or boss (c!., fig. 6), in colour and consistency 
exactly similar to the cilia themselves. This nodule may 
possibly be a rudiment of the velum described and figured 
by James Clark in Trichodina pediculus. 
Within the circle of motor cilia is the striated border 
(st. b., fig. land 2 seen obliquely). ‘This is composed of a per- 
fectly clear substance, marked by fine striz arranged radially. 
It does not appear to be rigid, but, as may be seen in fig. l, 
varies in breadth. ‘This variation is due apparently to 
different portions of it being placed simultaneously at various 
angles te the eye. In fact, when seen sideways, it could be 
perceived that this striated margin of the dise bent back- 
wards and forewards with a slow undulating movement 
(cf. fig. 2). The stria are on the anterior (¢.e. aboral) 
surface of the disc. A superficial set could not be distin- 
guished from a more deeply placed set, though such a dis- 
tinction was found by James Clark in T. pediculus.! These 
strie (fig. 1) are not quite regular, in some places seeming 
to be placed near together and then being fine, in others far 
apart and then coarse. At a spot where the cilia were moving 
the striated border appeared darkish and the strie very 
near together (aseg. on right side of fig. 1), so that 
probably the want of uniformity observed was really due to 
contractions in the substance of the disc itself and the con- 
sequent approach of the striz to one another. 
Next to the striated border and internally to it lies the 
1 «Annals and Mag. Nat. Hist.,’ 1866, p. 412, Pl. VIII, figs. 8, 10, 11, 
ie). De fle. Ay, 74 
2 Loe. cit., pp. 418, 414, Pl. IX, fig. 17, 2, 72, and 4, 2. 
