The body is cylindrical, crystalline, and appears almost empty; it has three pellucid points disposed lengthways, the apex is truncated in an oblique direction, the margin bent back. The upper part contracts itself, and the margin then assumes a conical shape, with a convex surface; there are in general but few branches from the principal stem, and these are short and thick. It excites an undulatory motion, but no hairs, nor any rotatory motion, have been discovered. Fig. 31, o and n, represents the vorticella adhering to the monoculus quadricornis.
VORTICELLA CONVALLARIA.
[Plate XXII.] Fig. 39.
Vorticella simplex, gregaria, flore campanulata mutico; tentaculis bigeminis, stirpe fixa. Simple, but gregarious, the florets bell-shaped, with two pair of little arms, and a fixed stem.
Vorticella simplex, campanulata, pedunculo rotortili. Müller Animal. Infus.
These vorticellæ, or bell-animals, as they are termed by Baker, are generally found adhering to some substance in the water; they are represented here as found by Rösel, fixed to a curious cornu ammonis, with points projecting from the back. To the naked eye they appear only as so many little white points, but under the microscope, as little bells, agitating the water to a considerable distance. The stems of these have a particular motion, they draw themselves up and shorten all at once, taking the form of a spiral wire or screw; in a moment after they again resume their former shape, stretching themselves out straight as before. Many of them may be seen at times adhering to each other by their tails; the cilia, which are two on each side of the mouths, are very seldom to be perceived.
VORTICELLA URCEOLARIS.
[Plate XXII.] Fig. 33, 34, 35, 36, 37, 38.
Vorticella simplex, pedunculata, ore dentato. Single, with a short tail, and toothed mouth.
Brachionus capsularis testa ovata apice sexdentata basi incisa, cauda longa bicuspi. Müller Animal. Infus. p. 356.