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Record: oai:ARNO:508455

AuthorR. Horst
TitleOn two remarkable species of Aphroditidae of the Siboga-Expedition
JournalNotes from the Leyden Museum
AbstractAt Station 282, off the North East point of Timor, at a depth of 27โ€”54 M., a single Polynoid-worm was kept, that is characterized not only by the singular shape of its elytra, but also by the abnormal manner of their attachment. For the elytra have not the usual appearance of flat, scale-like organs, that are attached at their under side, but they are represented by small oval buds, not quite so high as broad and fixed at their median side to a long elytrophore; there are 26 pairs of them, as in other Lepidasthenia-species situated on segment 2, 4, 5, 7, 9โ€”23, 26, 29โ€”65. They are quite smooth and without any appendages. About the internal structure of these organs ยน) I have observed, that like in other elytra there is an epidermis-layer of polygonal cells, ending at their base in fine fibres, forming a dense network in the centre of the organ; the presence of a nerve could not be stated with certainty, but they contain a great number of dark, yellowish, glandular (?) cells. The dorsal cirri are also very short and do not exceed the elytra much in length except at the anterior segments. The parapodia are very slender; in the posterior region they are (with the bristles) as long as the breadth of the body, in the anterior part they measure two thirds of it. The notopodial fascicle is absent and only represented by the acicula; the neuropodial bristles are faintly curved in their distal part and show a short subterminal dilatation with a small number of transverse spinous rows. The inferior setae of this fascicle have a simple undivided apex; however some of the superior ones have a bifurcated tip, the main point of which is elongated in a long, slender, acute limb, whereas the other limb measures about a third of it.
In my opinion the situation of the elytra in this species affords a new argument in favour of the morphological similarity of the elytron and the dorsal cirrus, for in Lepidasthenia sibogae the tubercula dorsalia (elytrontubercles) are not only totally absent, but the elytra are fixed at the extremity of long elytrophores, quite agreeing in their situation and appearance with the cirrophores.
Document typearticle
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