Finally, we have the fourth grand division of animals, the _Rayonnés_, or _Radiata_; which, for reasons already given, we may call _Radials_, or _Radiaries_. These are _Echinoderms_, _Intestinals_, (or rather _Entozoans_,) _Acalephes_, and _Polyps_. The Polyps, which are composite animals in which many gelatinous individuals are connected so as to have a common life, have, in many cases, a more solid framework belonging to the common part of the animal. This framework, of which coral is a special example, is termed in French _Polypier_; the word has been anglicized by the word _polypary_, after the analogy of _aviary_ and _apiary_. Thus Polyps are either _Polyps with Polyparies_ or _Naked Polyps_. Any common kind of Polyps has usually in the English language been called _Polypus_, the Greek termination being retained. This termination in _us_, however, whether Latin or Greek, is to be excluded from the English as much as possible, on account of the embarrassment which it occasions in the formation of the plural. For if we say _Polypi_ the word ceases to be English, while _Polypuses_ is harsh: and there is the additional inconvenience, that both these forms would indicate the plural of individuals rather than of classes. {337} If we were to say, 'The Corallines are a Family of the _Polypuses with Polyparies_,' it would not at once occur to the reader that the last three words formed a technical phrase. This termination _us_ which must thus be excluded from the names of families, may be admitted in the designation of genera; of animals, as _Nautilus_, _Echinus_, _Hippopotamus_; and of plants, as _Crocus_, _Asparagus_, _Narcissus_, _Acanthus_, _Ranunculus_, _Fungus_. The same form occurs in other technical words, as _Fucus_, _Mucus_, _Œsophagus_, _Hydrocephalus_, _Callus_, _Calculus_, _Uterus_, _Fœtus_, _Radius_, _Focus_, _Apparatus_. It is, however, advisable to retain this form only in cases where it is already firmly established in the language; for a more genuine English form is preferable. Hence we say, with Mr. Lyell, _Ichthyosaur_, _Plesiosaur_, _Pterodactyl_. In like manner Mr. Owen anglicizes the termination _erium_, and speaks of the _Anoplothere_ and _Paleothere_. Since the wants of science thus demand adjectives which can be used also as substantive names of classes, this consideration may sometimes serve to determine our selection of new terms. Thus Mr. Lyell's names for the subdivisions of the tertiary strata, _Miocene_, _Pliocene,_ can be used as substantives; but if such words as _Mioneous_, _Plioneous_, had suggested themselves, they must have been rejected, though of equivalent signification, as not fulfilling this condition.