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"These animals [the Rotifera], called <em>Wheel Animalcules</em>, were formerly included among the Infusoria, but are now classed with the Articulata: they are chiefly known to us by the microscope, the largest being not over a tenth of an inch long, and many of them only one three-hundredth of an inch." &mdash; Goodrich, 1859

Wheel, animalcule

"These animals [the Rotifera], called Wheel Animalcules, were formerly included among the Infusoria,…

"Brachionus rubens. A, from the dorsal aspect; B, from the right side. a, anus; br, brain; d. f. dorsal feeler; c. gl, cement gland; cl, cloaca; c. l, ciliary lobes; c. v, contractile vesicle; e, eye-spot; int, intestine; lr, lorica; l. f, lateral feeler; m, muscular bands; nph, nephridial tubes; ov, ovary; ph, pharynx; st, stomach; t, tail; tr, d, trochal disc; vt, vitellarium." -Parker, 1900

Brachionus Rubens

"Brachionus rubens. A, from the dorsal aspect; B, from the right side. a, anus; br, brain; d. f. dorsal…