. Boston journal of natural history. Natural history. On Arachnactis hrachiolata. 527 at one extremity of the longitudinal axis of the mouth we find the oldest tentacles, while at the other, tentacles are constantly added which belong to one and the same cycle, although not all formed at the same time. Besides these tentacles which are all in pairs, an odd tentacle is devel- oped opposite the extremity of the mouth nearest the edge of the disk. (Fig. 3.) The disk of specimens having as many as sixteen ten- tacles, (fig. 2,) is very elliptical, the whole body being strongly compressed laterally
. Boston journal of natural history. Natural history. On Arachnactis hrachiolata. 527 at one extremity of the longitudinal axis of the mouth we find the oldest tentacles, while at the other, tentacles are constantly added which belong to one and the same cycle, although not all formed at the same time. Besides these tentacles which are all in pairs, an odd tentacle is devel- oped opposite the extremity of the mouth nearest the edge of the disk. (Fig. 3.) The disk of specimens having as many as sixteen ten- tacles, (fig. 2,) is very elliptical, the whole body being strongly compressed laterally in the same direction as the slit of the mouth. (Fig. 3.) So that, when seen from the narrow side facing the odd tentacle or the youngest pair of tentacles, the appearance of the animal is quite different. In the first case the tentacles are arranged symmetrically on both sides of the small odd tentacle, (fig 4,) an uneven number of tentacles being seen; while in the second case there is an even number of tentacles seen arransfed on both sides of the prolongation of the longitudinal axis of the mouth, as in fig. 2. When seen from the broad side the aspect is still different, the tentacles decreasing regularly in size, after the second pair, from the extrem- ity where the odd tentacle is placed towards the part of the disk where the new tentacles are added. (Fig. 5.) This figure has only three pairs of ten- tacles, but the proportions of the dif- ferent tentacles always remain, in the specimens which I have seen, nearly like this, as can readily be seen from figure 2, which has six pairs of tenta- cles. When seen from the narrow side, the large tentacles are placed Figure :i from tue broaa symmetrically on both sides of the Tentacles of fig. 2 from the narrow side ficiui; odd 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 perfe
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