. The British freshwater Rhizopoda and Heliozoa. Rhizopoda; Heliozoa; Freshwater animals. QUADRULA. SYMMETRICA. 131 Test in broad view pyriform, the crown semi-circular; much narrower at the mouth, which has a slightly convex outline; the sides tapering convexly down- wards to the base; the structure compressed laterally. The transparent chitinous plates arranged in oblique series across the surface; usually smaller about the mouth than above, and not infrequently out of position. Plasma very clear, containing chlorophyl-corpuscles with other elements; the pseudopodia (usually 3-5) digitate; t
. The British freshwater Rhizopoda and Heliozoa. Rhizopoda; Heliozoa; Freshwater animals. QUADRULA. SYMMETRICA. 131 Test in broad view pyriform, the crown semi-circular; much narrower at the mouth, which has a slightly convex outline; the sides tapering convexly down- wards to the base; the structure compressed laterally. The transparent chitinous plates arranged in oblique series across the surface; usually smaller about the mouth than above, and not infrequently out of position. Plasma very clear, containing chlorophyl-corpuscles with other elements; the pseudopodia (usually 3-5) digitate; the single nucleus prominently situated in the upper region of the body. Dimensions : Variable; average length about 96 ju,; breadth 60-70 /a ; in dorsal (transverse) view about 40 Fia. 102.—Test of Quadrula symmetrica, x 375. In marshy ground amongst Sphagnum, etc.; some- times in moss growing on moist rocks; abundant and widely distributed. This beautifully-transparent species is usually abun- dant in boggy ground, where Sphagnum abounds. The disposition of the plates is not always symmetrical; they are sometimes seen pressed out of position, with, as a consequence, overlapping edges; frequently also the edges project beyond the margin of the test. Two forms are found—sometimes in the same gather- ing—one considerably broader in proportion than the other, but not otherwise essentially differing. Penard, in a paper communicated to the Royal Society of Edinburgh (March, 1905), " Sur les Sarco-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Cash, James, 1839-1909; Hopkinson, John, 1844-1919. joint author; Wailes, George Herbert, 1862-. London, Printed for the Ray Scociety
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