A. CO. Stokes—Fresh-water Infusoria. 43 
forming about’ one-third of the entire length of the body; 
‘cuticular cilia long and fine; peristome field a long channel 
‘occupying somewhat less than the anterior two-thirds of the 
left-hand border, taking its origin at a short distance posteriorly 
to the beak-like apex, the margin bearing the adoral cilia pro- 
jecting laterally, its outline sigmoid, its free edge conspicuously 
thickened ; adoral cilia long, continued around the mouth and ~ 
into the narrow, ciliated, anteriorly curved pharynx; the 
undulating membrane large, delicate and very flexible, its base 
of attachment extending obliquely within the adoral channel 
and about the posterior margin of the oral aperture; nucleus 
conspicuous, moniliform, more or less sigmoid, obliquely and 
subcentrally placed; contractile vesicle single, spherical, pos- 
teriorly located near the left-hand border at the base of the 
tail-like prolongation. Length of body s1, inch. Habitat— 
Standing water, among the residual detritus at the bottom. 
This noble infusorian is represented in figure 2, magnified 
about 880 diameters. Its habitat seems to be restricted to that 
just mentioned, as I have been unable, even after careful search, _ 
to take it elsewhere, and from thence only after the sediment 
has been disturbed and the animalcule captured before it could 
again bury itself. It is essentially a mud-loving form, and 
seems rare. I have taken but six individuals after prolonged 
searching.. The nucleus is commonly composed of from four 
to seven nodules, including the single one usually laterally 
attached. 
Tbe numerous scattered vacuoles are generally circular in 
optical outline; they frequently collect together near the 
median. line and gradually disappear. e larger, more con- 
spicuous one near the pulsating vesicle is commonly of irregu- 
lar outline and qnite persistent, seldom more than slightly 
changing its form 
Apgaria ovata, sp. nov. . 8).—Body irregularly ovate, 
length once and one-half to twice the breadth, the posterior 
. : 
