Crossopterygii

Part of these Crossopterygii approach very closely in their chief anatomic features to the Dipneusts, and thus represent phylogenetically the transition from the Devonian Ganoids to the earliest air-breathing vertebrates.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

Among the paleozoic plated fishes or Ganoids the Crossopterygii and the Ctenodipterina (dipneusts) are of great importance.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

In many impressions of the Crossopterygii the floating bladder seems to be ossified, and therefore well preserved -- for instance, in the Undina (Figure 2.254, immediately behind the head).

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

Huxley, to whom we owe particularly important works on the fossil Ganoids, classed them in the order of the Crossopterygii.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

In many of the Crossopterygii the wall of the bladder is covered with bony plates, as in the Triassic Undina (Figure 2.254).

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876