Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/275

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As the place of the syphon in 'this species is upon the internal margin of the transverse plates (Pl. 43; Fig. 2 b1, b2, b3,) it had less power than the more central siphuncle of the Nautilus to attach the mantle of the animal to the bottom of the outer chamber. For this defect we find a compensation, resembling that which Von Buch considers to have been afforded by the lobes of Ammonites to the inhabitants of those shells. This compensation will be illustrated by a comparison of the lobes in N. Sypho (Pl. 43, Fig. 2.,) with a similar provision in the Nautilus Zic Zac (Pl. 43, Figs. 3, 4)