. Catalogue of casts of fossils, from the principal museums of Europe and America, with short descriptions and illustrations. Fossils. PTEROPODA. No. 641. Bucania expansa, Hall. This loosely coiled, trumpet-mouthed shell is from the Tren- ton Limestone (Lower Silurian) of Watertown, N. Y. Price, $ No. 643. Strophostylus cyclostomus, Hall. From the Niagara limestone (Upper Silurian), Waldron, Ind. Price, $ No. 643. Trails of G-asteropoda, From the Clinton group (Upper Silurian), New Hartford, N. Y. Price, $ CLASS III.—PTEROPODA. These small Cephalous Molluscs are so called from t
. Catalogue of casts of fossils, from the principal museums of Europe and America, with short descriptions and illustrations. Fossils. PTEROPODA. No. 641. Bucania expansa, Hall. This loosely coiled, trumpet-mouthed shell is from the Tren- ton Limestone (Lower Silurian) of Watertown, N. Y. Price, $ No. 643. Strophostylus cyclostomus, Hall. From the Niagara limestone (Upper Silurian), Waldron, Ind. Price, $ No. 643. Trails of G-asteropoda, From the Clinton group (Upper Silurian), New Hartford, N. Y. Price, $ CLASS III.—PTEROPODA. These small Cephalous Molluscs are so called from the resemblance of their chief organs of motion to a pair of wings. They are either naked, or provided with a delicate translucent shell. In their first stages, they exactly resemble the Gastropod fry; and accordingly Lamarck, De Blainville and Owen regard them as a sub-class of the Crawlers, but Cuvier, Woodward, and Jones give them a higher rank. The active Clio (the food of whales and sea-birds) has its head armed with 360,000 microscopic suckers—a prehensile apparatus perhaps unequalled else- where in creation. The shell, when existing, resembles either a univalve or a bivalve in which the two valves have been cemented along the hinge. These " sea-butterflies," as they have been called, float in mid- ocean in every latitude, forever out of sight of land. There are 32 fossil species,—all from the Tertiary, excepting the gi- gantic Theca, and Conularia, which are Silurian. No. 644. Conularia undulata, Conrad. The Conularke. are commonly referred to this Class ; hut their large, thin, pyramidal shells, chamhered at the apex and admitting of some motion at the angles above, present some of the distinctive features of Cephalopods. If really pteropodous, they were the giants of the Class. The angles of the Conularia are grooved, and the sides are striated transversely. This speci- men is from the Hamilton group (Devonian), Cazenovia, N. Y. Price, $ No. 645. Co
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectfossils, bookyear1866
