. Natural history. Geology; Zoology; Botany. 14 W. a. EIDEWOOD. the ostium, are common (Harmer, 10, p. 9 and fig. 12). The disposition of these rings, complete and incomplete, is more clearly marked in C. levinseni than in C. nigrescens, for in the latter the common portion of the test that fills in the interval between one tube and the next (" external secondary lamellae " of Harmer) is more abundant, and only the terminal portions of the tubes stand out freely. The mode of deposition of the material in C. nigrescens is illustrated in figs. 12 and 13 of plate 4, and reference to the
. Natural history. Geology; Zoology; Botany. 14 W. a. EIDEWOOD. the ostium, are common (Harmer, 10, p. 9 and fig. 12). The disposition of these rings, complete and incomplete, is more clearly marked in C. levinseni than in C. nigrescens, for in the latter the common portion of the test that fills in the interval between one tube and the next (" external secondary lamellae " of Harmer) is more abundant, and only the terminal portions of the tubes stand out freely. The mode of deposition of the material in C. nigrescens is illustrated in figs. 12 and 13 of plate 4, and reference to the latter of these will show that not only may the secreted material spread over from the tube-margin to the interval between the tube in question and its neighbours, but that thin films are continued down the inner surface of the tube ("inner secondary lamellae" of Harmer). These secondary lamellae, both inter-tubular and intra-tubular, appear to have no existence in Text-Figure 7.—Rhabdopleura rwrmani. A, — portion of a colony, highly magnified. (Copied from Lankester, 13, plate 89, fig. 1.) B, — terminal portion of a tube, more highly magnified. (Copied from Harmer, 10, plate 2, fig. 19.) a, extremity of a growing branch ; 6, gymnocaulua or soft stalk of the terminal polypide of the growing branch; c, latest bud produced by the gymnocauluB; d, penultimate bud; the part of the stalk which produced it has now become hardened, and is known as pectooaulus; e, third bud; it has forced its way through the wall of the axial tubarium, and is constructing a lateral tube; /, fourth bud, counting from youngest; it is now a fully-formed polypide, with complete polypide-tube with recumbent and vertical portions; g, fifth bud; h, pectocaiUus; j, j, septa of axial portion of tubarium. The mode of bud-succession of Rhabdopleura is not paralleled in Cephalodiscus. The terminations of the branching colony of Rhabdopleura are, as Lankester has shown, of two kinds,
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