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Leptaena rhomboidalis (Silurian). A, External view of ventral valve.; B, Interior of ventral valve; a, occlusor scars; d, pseudo-deltidium; d,f, divaricator scars; c,a, hinge are; t, teeth
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Stages in the development of the larva of Terebratulina septentrionalis.... The youngest larva has two segments, a third then appears, the larva then fixes itself, and the second segment folds over the first and develops bristles round its edge.
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Terebratula sella (Lower Greensand) d, Deltidium; f, foramen.
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Three specimens of Crania anomala on a stone dredged in Loch Fyne. The topmost specimen is seen in profile.
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Brood-pouch of Thecidium mediterraneum. Part of the wall of the pouch has been removed to show the clusters of larvae.. 1. Mouth, overhung by lip.; 2. One of the two median tentacles which are enlarged and modified to bear the larvae.
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Muscle-scars of Lingula anatina. Inner survace of A, Pedicle-valve or ventral valve. B, Brachial or dorsal valve..
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Productus giganteus. Carboniferous Limestone.. A, Interior of dorsal valve.; B, Interior of ventral valve.
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Figures illustrating the tubes in which Lingula anatifera lives. The upper figure is a view of the trilobed opening of the tube. The lower figure shows the tube in the sand laid open and the animal exposed. The dotted line indicates the position of the body when retrcted. The darker portion is the tube of sand agglutinated by the secretion of the stalk..
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Young larva of Cistella neapolitiana showing three segments, two eye spots, and two bundles of setae.
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Full-grown larva of Cistella neapolitiana with umbrella-shaped head, ciliated..
