. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. from the North Pacific Ocean. 443 into two, and each half bear at its extremity a fresh series of branches, a new colony. The hydrothecte are arranged in ten regular series ; but this character is not perfectly constant; sometimes, although rarely, we meet with very slender branches which have only seven or eight series; and, further, the number ten appears to be most constant at the ends of the branches, where it is almost always met with; whilst towards the point of attachme
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. from the North Pacific Ocean. 443 into two, and each half bear at its extremity a fresh series of branches, a new colony. The hydrothecte are arranged in ten regular series ; but this character is not perfectly constant; sometimes, although rarely, we meet with very slender branches which have only seven or eight series; and, further, the number ten appears to be most constant at the ends of the branches, where it is almost always met with; whilst towards the point of attachment the number very often diminishes, becoming nine, eight, and sometimes seven, or even six. The great number of series causes the branches to be very thick ; in this species they attain the greatest thickness that I know. The hydrothecse are arranged so as to form not only longi- tudinal series, but also a very regular spiral line around the axis (PI. XVII. fig. 15). This character is not the exclusive pecu- Fic Fie Fk. 1. c: f^ 1st , series. /'uj'' o '^: 2nd series. Biserial type. 2nd series. 3rd series. Type luultiserial by Type multiseiial by torsion. liarity of Selaginopsis decemserialis, but, as we have already seen, it belongs also to the other species that I have described ; throughout we have found that no two orifices of the more or less numerous seines ever come at the same level. This spiral arrangement, which, as I believe, iscommon to the whole genus, renders it possible to attempt an explanation of the polyserial type, not by means of the displacement of the hydrothecse of each series in the biserial type (that is to say, by the divi- sion of each series into two, three &c.), but simply by the torsion of the axial tube, which would produce a spiral and,. 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 r
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