Page:Popular Science Monthly Volume 11.djvu/207

Rh Lepidosteus; and the geological, the zoölogical, and the embryological series, upon the whole, have a recognizable correspondence.

So far, the writer has endeavored to give an outline of the natural history of the gar-pike as a peculiar American fish, concerning which little has hitherto been published even in strictly scientific works, and almost nothing in a form generally accessible.

In so doing he has purposely avoided the presentation of controversial points, or, in reference to the nomenclature of the air-bladder and of the tail, has presented opposing views, with an abstract of the evidence, so far as known to him; admitting his inability, as yet, to form a definite conclusion.

But there is another and, in some respects, most interesting and important light in which the gar-pike may be considered, namely, as to its relations with other fish-like forms.

Is Lepidosteus merely a somewhat peculiar fish? Or may it, with Polypterus and some fossils, be separated as a distinct group? Or should there be added to this group Amia and the sturgeons? Or should the catfishes and their kindred, with the pipe-fishes, globefishes, and others, be likewise included?

Upon what grounds may this group be defined? What is its grade, class, sub-class, or order? And how may it be subdivided?

Attempts have been made to find answers to these questions by the study of the scales, the skeleton, the limbs, the gills, and various internal organs. The embryology of the sturgeons is not fully known, while nothing whatever has been observed of the earlier stages of the so-called typical Ganoids.

It is probably within the truth to say that, from the time of Cuvier down, no two authors upon fishes agree upon all the points, while any contemporary discussion, whether verbal or in print, is almost certain to be attended with a degree of heat quite incompatible with the apparent importance of the subject.

The fact is, however, that the so-called Ganoids occupy a very peculiar position. None of them can be touched without affecting the entire series of fish-like forms. Ichthyology is in a state of instability, and every important new fact, every decided expression of opinion by high authority respecting the Ganoids is liable to require a revision of all our ideas.

To present even an outline of the many views, and of the facts and considerations upon which they are based, would require an entire article, with many figures and some anatomical description.

To the reader who has become interested by the foregoing imperfect sketch of the gar-pike, and who has the good fortune to live within reach of it, of Amia, and of the sturgeons, the writer would earnestly recommend a careful and systematic investigation of their habits and their structure—especially that of the brain—and of their development, as likely to furnish the most reliable basis for their classification.