United States or Philippines ? Vote for the TOP Country of the Week !
Lepidotus Mantelli, Agassiz. Wealden. a. Palate and teeth. b. Side view of teeth. c. The fishes of the Wealden are chiefly referable to the Ganoid and Placoid orders. These ganoids were allied to the Lepidosteus, or Gar-pike, of the American rivers. The whole body was covered with large rhomboidal scales, very thick, and having the exposed part coated with enamel.
The ganoid fish seemed to prove to him that it had selected neither new form nor new force, but that the curates were right in thinking that force could be increased in volume or raised in intensity only by help of outside force.
The only modification which it occurs to me to suggest in this general view of the Phylogeny of the Vertebrata is, that the "Protamphirhine" was possibly more ganoid than shark-like.
The greater part of these bore impressions of primitive organisms. Creation had evidently advanced since the day before. Instead of rudimentary trilobites, I noticed remains of a more perfect order of beings, amongst others ganoid fishes and some of those sauroids in which palaeontologists have discovered the earliest reptile forms.
Their scales are also peculiar, being covered by enamel so hard, that, if struck with steel, they will emit sparks like flint. It is on account of this peculiarity that the whole group has been called Ganoid. Now, though we have not found as yet any complete specimens of Silurian fishes, their disconnected remains are scattered profusely in the early deposits.
Ammophila, on the jaws of. Ammotragus tragelaphus, hairy forelegs of. Amphibia, affinity of, to the ganoid fishes; vocal organs of the. Amphibians, breeding whilst immature. Amphioxus. Amphipoda, males sexually mature while young. Amunoph III., negro character of, features of. Anal appendages of insects. Analogous variation in the plumage of birds. Anas. Anas acuta, male plumage of.
Probably arthropods and vertebrates were threatened with it too. They escaped, however, and to this fortunate circumstance is due the expansion of the highest forms of life. In two directions, in fact, we see the impulse of life to movement getting the upper hand again. The fishes exchanged their ganoid breast-plate for scales.
Word Of The Day