A treatise on zoology . >, pelvic bone; are ventral and behind thp mouth 7->•, preaxial radial, or remains of axis. (Partly tue veiiLiai anu ueninu tne mouin. ^^^^^ Davidoff, from Quart. Joum. Mirr. .sd.) In the Teleostei the yolk is rela-tively very large in amount and the cleavage meroblastic. Fre-quently their eggs float freely in the sea with the help of an oil-globule of light specific gravity (Dean [105], Agassiz [3], pjalfour[30], etc.). The orders Ganoidei, Ctenoidei, and Cycloidei of Agassiz(p. 210), founded merely on the structure of the scales, were shownby Johannes Midler to
A treatise on zoology . >, pelvic bone; are ventral and behind thp mouth 7->•, preaxial radial, or remains of axis. (Partly tue veiiLiai anu ueninu tne mouin. ^^^^^ Davidoff, from Quart. Joum. Mirr. .sd.) In the Teleostei the yolk is rela-tively very large in amount and the cleavage meroblastic. Fre-quently their eggs float freely in the sea with the help of an oil-globule of light specific gravity (Dean [105], Agassiz [3], pjalfour[30], etc.). The orders Ganoidei, Ctenoidei, and Cycloidei of Agassiz(p. 210), founded merely on the structure of the scales, were shownby Johannes Midler to be to a great extent artificial. Followingrather the example of Cuvier, and trusting chiefly to distinctions ofinternal anatomy, Miiller determined the limits of the groupGanoidei anew [307], purging it of its foreign elements. Hedivided Agassizs three orders into two sub-classes, the Ganoidei. 278 TELEOSTOMI and Teleostei, placing two orders in the former, the Holostei{Lepidosteus and PoJypteru>^) and the Chondrostei (Acipenserini andSpatulariae). Thus was hiid the foundation of our modern classifica-tion. Miillers Ganoidei are distinguished from the Teleostei bythe possession of a valvular contractile conus, a spiral valve, and anoptic chiasma. C. Vogt [?474(] subsequently showed that Amiabelongs to this group. The next great step Avas made by Huxley [227]. Ti-eating thefossil in conjunction with the living fish, he subdivided theGanoidei into Amiadae, Lepidosteidae, Crossopterygidae, Chon-drosteidae, and Acanthodidae. The foundation of the groupCrossopterygidae was a great advance, for in it were gathered together with Iohjptenis anumber of related but hithertoscattered genera clearl} dis-tinguished from the remainderof the Ganoidei. On theother hand, the work of Cope,A. S. Woodward, and otherson extinct fish has tended tobreak down the distinctionbetween the Ganoide
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