[110] Natural History of the Polype.
[111] The hydræ or polypes have generally been denominated Insects: is there not a manifest impropriety in the application of this term to them? If we admit of the systematic arrangement of Linnæus, we find that he has divided the animal kingdom into six classes: 1. Mammalia. 2. Aves. 3. Amphibia. 4. Pisces. 5. Insecta; and 6. Vermes. Of the last or Vermes, the Zoophytes (from ζωοφυτον, or animal plant) constitute the fifth order. He defines it as Animalia composita, efflorescentia more vegetabilium: amongst these he includes the various species of Vorticellæ and Hydræ.
The term animalculæ, or small animals, is certainly not inapplicable to them, but they differ materially in the peculiar characteristics by which insects are distinguished, see [page 179], and [pages 215]-[220]. They do not undergo those transformations to which insects are subject, and which have been so fully described in the preceding part of this work: their figure, habits, and œconomy are also very different. In short, they seem to be in every respect, except their minuteness, quite a distinct race of animated beings, as will be more fully exemplified in the following pages. Edit.
[112] Lin. Syst. Nat. p. 1320.
This animal fixes itself by its base, it is gelatinous, linear, naked, can contract itself, and change its place. Its mouth, which is at one end, is surrounded by hair, like feelers. It sends forth its young ones from its sides, which drop off.
1. Hydra viridis, tentaculis subdenis brevioribus.
Green polype, generally with about ten short arms; it is represented in [Plate XXI.] Fig. 5.
2. Hydra fusca, tentaculis suboctonis longissimis.
This polype has very long arms, often eight in number; it is represented at [Plate XXI.] Fig. 7. The arms are several times longer than the body.
3. Hydra grisea, tentaculis subseptenis longioribus.