A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . e of Piloceras, the dotted lines being reconstructed; sw, shell-wall;s, chambers divided by septa, whose necks form the wall (w) of thewide neck-tube; sc, s^Dace occupied by visceral cone, the hardenedskin of which forms the sheath (sh); r, remains of similar sheaths;e, endosiphon. (After Foord). b, Orthoceras; in the lower part theshell-wall is preserved ; then it is partly removed, showing the filling ofrock or matrix; higher up this is cut through, and at the t
A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . e of Piloceras, the dotted lines being reconstructed; sw, shell-wall;s, chambers divided by septa, whose necks form the wall (w) of thewide neck-tube; sc, s^Dace occupied by visceral cone, the hardenedskin of which forms the sheath (sh); r, remains of similar sheaths;e, endosiphon. (After Foord). b, Orthoceras; in the lower part theshell-wall is preserved ; then it is partly removed, showing the filling ofrock or matrix; higher up this is cut through, and at the top it isremoved, showing the other side of the shell. arise a narrow and empty tube—the siphuncle. The walls,however, were stiffened with lime and did not completelyyield to the suction, so that, when the animal again advanced,the inner layers of the skin were torn away from the outerones. These inner layers thickened and stiffened in theirturn, and the process was repeated. Thus arose the thintube, sometimes called the endosiphon, and a series of sheathsattached to it. In Orthoceras and similar forms there is an advance on.
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Keywords: ., bookauthorbr, bookcentury1900, bookdecade1900, booksubjectfossils
