[116] Hydra hydatula habitat in abdomine mammalium, ovium, suum, murium, &c. inter peritoneum et intestina. Vesica lymphatica, pellucida, magnitudine pruni, petiolata corpore cylindrico, in cujus apice os, quod, corpore compresso, movet tentacula vix manifesta. Linn. Syst. Nat. p. 1321, No.5. OF THE HYDRA STENTOREA. Plate XXII. Fig. 27 and 28. Hydra tentaculis ciliaribus corpore infundibuliformi. The arms of this hydra are rows of short hairs, the body trumpet-shaped. This species of hydra is very common, and has been described by almost every writer on these subjects; it is placed by Müller among the vorticellæ. Vorticella stentorea caudata, elongata, tubæformis limbo ciliato. Müller animalcula infusoria. Mr. Baker originally named it the funnel-like polype, which Messrs. Trembley and Reaumur changed to the tunnel-like polype, under which name it appears in the Philosophical Transactions, No. 474. There are three kinds of them, which are of different colours, green, blue, and white. The white ones are the most common. It is necessary to observe them often, and in various attitudes, in order to obtain a tolerable idea of their structure. They do not form clusters, but adhere singly by their tail to whatever comes in their way; their anterior end is wider than the posterior, and being round, gives the animal somewhat of a funnel form, though it is not completely circular, having a sort of slit or gap that interrupts the circle. The edge of this opening is furnished with a great number of fibrillæ, which by their brisk and continual motions excite a current of water; the small bodies that float or swim near this current, are forced by it into the mouth of the little animal. Trembley says, that he has often seen a number of very small animalcula fall one after another into the mouth, some of which were afterwards let out again at another opening, which he was not able to describe. They can fashion their mouths into several different forms. If any thing touch them, they shrink back and contract themselves. They live independent of each other, swimming freely through the water in search of their prey, and fix to any thing they meet with. These animals multiply by dividing themselves, not longitudinally, nor transversely, but sloping and diagonal wise; the proceedings in nature continually varying in every new form of life. Of the two polypes produced by the division of one, the first has the old head and a new tail; the other, the old tail and a new head.