Catalogue of the college series of casts of fossils; from the principal museums of Europe and America, with short descriptions and illustrations Henry Augustus Ward
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ISBN : 1130311252
Author : Henry Augustus Ward Download Here http://bit.ly/ebook_apetiga
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1870 Excerpt: ...grit. As the Cartilaginous Fishes dwindled the Teleosts took their place. They began in the Cretaceous, but abounded most in the Tertiary deposits. Respecting fossil Pishes, Agassiz says: "I have not yet found a single species which' was perfectly identical with any marine existing Fish, except the little Capelin (Mallotus villosus), which is found in the nodules of clay of unknown age in Greenland." The "Scomberoids" (the Mackerel tribe), observes Owen, "seem now to be at the head of the piscine modification of the Vertebrate series." The ancient Placoids and Ganoids, however, were more highly organized than the modern Cycloids and Ctenoids, and manifested a closer affinity to the airbreathing, cold-blooded Class. Order 1--G Avoids. The Ganoids, represented now by the Sturgeon, Gar Pike and others, have a skeleton, cartilaginous or ossified, rhomboidal or angular scales, and labyrinthoid teeth. No living Ganoid has been observed in the Southern Hemisphere. Of fossil Ganoids, 80 are found in the Devonian, 61 in the Carboniferous, 22 in the Magnesian Limestone, 23 in the Trias, 100 in the Lias, 154 in the Oolite, 36 in the Chalk, and 29 in the Tertiary. After the Triassic Period, they lost the Palaeozoic feature of heterocercal tails. The Devonian species have many reptilian characters; they are often found in nodules of a flattened, elliptic form, such nodules being created by the oil of the decomposing Fish rendering the surrounding sand compact. The Placoganoids, which first appeared in the Upper Silurian, died out in the Carboniferous. The Lepidoganoids ranged from the Devonian to the Tertiary. Evidence of a true Sturgeon has not been met with below the Eocene clay of Sheppey. The Oolitic Fishes are generally homocercal Gano...
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