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Fig. . Crissatella mucedo; an adult specimen, adhering to the submerged stem of Ranunculus

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DESCRIPTION OF THE PLATES.

PLATE I.

CRISTATELLA MUCED.o.

aquasilis. Of the natural size. The same enlarged.

Statoblast of Crissatella mucedo in an early stage; it is surrounded by a ciliated mem

brane, and there is as yet no appearance of the marginal spines.

. The same more advanced; the enveloping membrane is destitute of cilia, and the spines

have begun to grow out from the margin of the disc.

. The same, still further advanced ; the spines have impinged on the enveloping mem

brane. The mature statoblast; the enveloping membrane has been torn by the pressure of the spines, and has disappeared, and the statoblast has become free.

. The same, viewed on the edge. Figs, 3–7 are magnified about 50 diameters. . Natural size of mature statoblast.

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Fig. . Lophopus crystallinus; specimens attached to the roots of Lemma polyrhiza. Natural

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10. ll. 12. 13.

14. 15.

PLATE II.

LOPHOPUs crystALLINUs.

S126. The same enlarged; adult specimen. The same; young specimen, with two polypides. Statoblast of Lophopus crystallinus, magnified about 50 diameters; viewed in face. The same, viewed on the edge. Portion of internal or hepatic layer of stomach. Three isolated cells of this layer further magnified. Each cell is seen to contain within it a secondary cell, with brown contents. Middle layer of stomach, composed of cells with colourless contents, and brilliant nucleus.

. Structure of the endocyst; the tissue has been treated with acetic acid, and presents

isolated nuclei, and nucleated cells in various stages of formation. Muscular network of the endocyst. Muscular fibre from the endocyst more highly magnified, and treated with acetic acid. An isolated muscle-cell of the same, still more highly magnified. Tubular network, containing peculiar corpuscles, occasionally seen in the substance of the endocyst. Corpuscles of the tubular network isolated. The same, under the action of acetic acid.

16–23. Parasitical organisms from the perigastric fluid of Lophopus crystallinus.

24.

Semi-ideal view of part of the lophophore and tentacular crown of Lophopus, showing the mouth and neighbouring parts, with the distribution of the nerves. The tentacula are partially removed, so as to bring into view the upper surface of the lophophore.

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