The bowfin reaches a length of two and one half feet, the male being smaller than the female and marked by an ocellated black spot on the tail. Both sexes are dark mottled green in color. The flesh of the species is very watery, pasty, much of the substance evaporating when exposed to the air. It is ill-flavored, and is not often used as food. The species is very voracious and extremely tenacious of life. Its well-developed lung enables it to breathe even when out of the water, and it will live in the air longer than any other fish of American waters, longer even than the horned pout (_Ameiurus_) or the mud-minnow (_Umbra_). As a game fish the grindle is one of the very best, if the angler does not care for the flesh of what he catches, it being one of the hardest fighters that ever took the hook. [Illustration: FIG. 25.—Bowfin (female), _Amia calva_ Linnæus. Lake Michigan. ] The _Amiidæ_ retain many of the Ganoid characters, though approaching more nearly than any other of the Ganoids to the modern herring tribe. For this reason the name _Halecomorphi_ (shad-formed) was given to this order by Professor Cope. The gular plate found in Amia and other Ganoids reappears in the herring-like family of _Elopidæ_, which includes the tarpon and the ten-pounder. Woodward unites the extinct genera called _Cyclurus_, _Notæus_, _Amiopsis_, _Protamia_, _Hypamia_, and _Pappichthys_ with _Amia_. _Pappichthys_ (_corsoni_, etc.), from the Wyoming Eocene, is doubtless a valid genus, having but one row of teeth in each jaw, and _Amiopsis_ is also recognized by Hay. Woodward refers to _Amia_ the following extinct species: _Amia valenciennesi_, from the Miocene of France; _Amia macrocephala_, from the Miocene of Bohemia; and _Amia ignota_, from the Eocene of Paris. Other species of Amia are known from fragments. Several of these are from the Eocene of Wyoming and Colorado. Some of them have a much shorter dorsal fin than that of _Amia calva_ and may be generically different. [Illustration: FIG. 26.—_Megalurus elegantissimus_ Wagner. Family _Amiidæ_. (After Zittel.) ] The genus _Megalurus_ differs from _Amia_ in the still shorter dorsal fin, less than one-third the length of the back. The body is elongate and much depressed. _Megalurus lepidotus_ and several other species are found in the lithographic stones of Bavaria and elsewhere. =The Oligopleuridæ.=—In the extinct family _Oligopleuridæ_ the scales are cycloid, the bones of the head scarcely enameled, and the vertebræ well ossified. Fulcra are present, and the mouth is large, with small teeth. The genera are _Oligopleurus_, _Ionoscopus_, and _Spathiurus_, the species not very numerous and chiefly of the Cretaceous. _Ionoscopus cyprinoides_ of the lithographic shales of Bavaria is a characteristic species.