This trichoda is rather thick in the middle, and pellucid, with a few molecules here and there, the sides obtuse, the fore-part ciliated with very fine hairs, the hind part terminating in a kind of bristles.

250. Trichoda Cyllidium.

T. ovata, apice hiante, basique crinita. [Plate XXVII.] Fig. 15. Egg-shaped, the apex gaping, the base hairy.

Pellucid, the hinder extremity filled with globules of various sizes, the fore-part narrower, without any appearance of an external organ. It vacillates upon the edge, commonly advancing on its flat side, and continually drawing in water; it then gapes, and opens into a very acute angle, almost to the middle of the body; but this is done so instantaneously, that it is scarcely perceptible. a, the mouth; b, the hairs or bristles, which it extends when nearly expiring.

251. Trichoda Cursor.

T. ovata, antice crinita, postice duplici pilorum strictorum et curvorum fasciculo. Oval trichoda, the fore-part hairy, and the hinder-part also furnished with some straight and curved hairs in two fascicles.

The body is flat and filled with molecules; in the fore-part is an oblong empty space, into which we may sometimes see the water sucked in.

252. Trichoda Pulex.

T. ovata, antice incisa, fronte et basi crinita. [Plate XXVII.] Fig. 12. Egg-shaped, with an incision in the fore-part; the front and base hairy. a, the anterior part; b, the posterior part; c, the incision.

253. Trichoda Lynceus.