The animal kingdom : arranged after its organization, forming a natural history of animals, and an introduction to comparative anatomy . 342 MOLLUSCA. fissure; from the exterior surface being marked with a longitudinal gutter on one side, or with two orseveral gutters towards the summit; or as that surfaee is smooth and without gutters. Some fossils, very much Uke the Belemnites, but without a cavity, and even with a protruding basis,form the genus Actiiwcamtuv of Miller. It is upon similar conjectures that the classification of the Ammonites, Brug., or Snake-stonkp,—Is founded, for they, also
The animal kingdom : arranged after its organization, forming a natural history of animals, and an introduction to comparative anatomy . 342 MOLLUSCA. fissure; from the exterior surface being marked with a longitudinal gutter on one side, or with two orseveral gutters towards the summit; or as that surfaee is smooth and without gutters. Some fossils, very much Uke the Belemnites, but without a cavity, and even with a protruding basis,form the genus Actiiwcamtuv of Miller. It is upon similar conjectures that the classification of the Ammonites, Brug., or Snake-stonkp,—Is founded, for they, also, arc only found in a fossil state. They are distinguished, in general, fromNautilus, by their septa, whieli, instead of being plain or simply concave, are angulated, sometimes undulated, but oftener gashed on the margins,like the leaves of the Acanthus. The smallnessof their last cell leads to the belief that, like theSpirula, they were internal shells. The beds ofthe secondary mountains swarm with them, andwe find them there from the size of a beanto that of a chariot wheel. The variationsof their whorls and of their syphon en
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Keywords: ., bookauthorwe, bookcentury1800, bookdecade1840, booksubjectanimals
