. Catalogue of casts of fossils, from the principal museums of Europe and America, with short descriptions and illustrations. Fossils. 142 MOLLUSCA. CLASS IV.—LAMELLLBRANCHIATA. These ordinary, leaf-gilled bivalves are generally free and locomotive;— a few, as the Oyster, are fixed. They are mostly equivalve (the ex- ceptions occurring in the stationary species), and always unequilateral. Each valve is a cone—of every grade from a flat plate to a spiral—, and the valves are articulated by teeth and a ligament, and also attached to each other by one or two muscles. The animal lives by filtering
. Catalogue of casts of fossils, from the principal museums of Europe and America, with short descriptions and illustrations. Fossils. 142 MOLLUSCA. CLASS IV.—LAMELLLBRANCHIATA. These ordinary, leaf-gilled bivalves are generally free and locomotive;— a few, as the Oyster, are fixed. They are mostly equivalve (the ex- ceptions occurring in the stationary species), and always unequilateral. Each valve is a cone—of every grade from a flat plate to a spiral—, and the valves are articulated by teeth and a ligament, and also attached to each other by one or two muscles. The animal lives by filtering water through its gills, which are distinct from the mantle. Nearly all have a muscular foot developed from the ventral surface The Lamellibranchs, according to Agassiz, differ from the Brachiopods only in " secondary ; They do not readily group themselves into natural orders : the similarity of type is great, and the points of difference are not constant. The Veneridse are the typical and most highly organized Lamellibranchs. These bivalves, though less numerous now specifically, are far more abundant individually, than the Gastropods. They are all marine, excepting a few widely dispersed fresh-water genera (10 out of 90), and are found on every coast and in every climate, and from low water to the depth of 200 fathoms. The fossil forms constitute a third part of fossil shells. The genera are seven times more numerous in the newer Tertiary than in the Cambrian; while there are 800 species in the Mio- eene, and only 100 in the entire Silurian series. Of 49 from the Lower Silurian of New York, 26 are restricted to the Trenton Limestone. No. 646. Ostrea Marshii, This and the eight following ferms belong to the family Ostreidce, being unequivalved and unequilateral, and having one muscular impression. From the Lias, Geislingen, Wirtemberg, and now in the Ward Museum, University of Rochester. Price, $ Please note that these images are ex
Size: 1488px × 1678px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, booksubjectfossils, bookyear1866
