Elements of Physiophilosophy

by Lorenz Oken

Tenth Class.

Osteozoa, Glossozoa—Pisces.

3533. No one of the upper classes is in such an extensive state of confusion as that of Fishes. Nor does this result simply from the great deviations in their structure from the normal type, these being rather useful than otherwise for the purposes of classification; but mainly from the utter want of any principle which might serve systematists as a guide. Thus at one time we find them having recourse to the nature of the osseous tissue, at another to the fins, now to the teeth or to the scales, ay, even to the fin-rays, and all this because the characteristic or typical organ has never been sought after, nor the presence of such an organ as indispensable been so much as known.

3534. The characteristic organ of Fishes is the Osseous system, which is consequently the principle also of their division.

The physical nature, form, position, and number of the osseous parts must therefore be principally considered, and hence, above all, the substance or texture of the bones; the limbs also, and the maxillæ with their teeth, as well as the teeth upon the palate, upon the tongue and the branchial arches.

With regard to the component substance or texture of the bones we encounter a great difficulty. The Cartilaginous Fishes appear to belong to each other, and are also usually arranged together. Yet amongst them we find those species, such as the Lampreys, which obviously occupy the lowest grade of all Fishes, while the Sharks and Rays remind us of the Reptilia and Thricozoa, as well by their external structure as the development of their sexual parts, since they possess perfect testes, and ovaria separate or distinct from the oviducts, while they no longer deposit roe, but large ova inclosed in leathery shells, like the higher Reptilia. Now, if we separate these Fishes from the Lampreys, with whom in the scaleless tegument, the branchial foramina, and even the external form they have many points of resemblance, nothing else remains to be done than assign them the uppermost place, and so parallelize them with the Thricozoa. But one is next constrained to unite into one family the Pikes and Herrings, which perhaps admits of being done.

There belong namely to the upper Fishes without doubt the Abdominales, which are divisible into five families: the Carps, Pikes, Shads, Salmons, and Herrings. Now, if the Sheat-fishes be placed inferiorly on account of their scaleless body and amorphous maxillæ, four families will still be left, which should correspond to the Fishes, Reptiles, Birds, and Thricozoa, so that no place is left remaining for the Sharks. Now, however, the Salmons correspond decidedly to the Reptilia; and the Flying Fishes, which are ranged below the Pikes, probably to the Birds. If we unite them with the Herrings, then the Sharks may occupy the place of the Thricozoa.

This being preassumed, we can now attempt the classification. The substance or texture of the bones is of such importance, that notwithstanding the separation of the Sharks and their congeners, the other Cartilaginous Fishes must be left along with them, and range upon the lowest stage, so that they thus correspond to the Intestinal animals.

The next great distinction in the osseous system is the regular and irregular form which it imparts to the body, so that the Regular-shaped can be separated in a tolerably "tranchant" manner from the Irregular Fishes.

The regular form of a Fish is obviously the ellipse, as we find to be the case in our fresh-water Fishes, namely, the Perches, Salmons and Carps. They are collectively covered with large scales, which is therefore also a sign of their regularity.