. Fig. 9. Serolis exigua, Nordenstam, (J : x 12. keel which is continued backwards as a spiniform process to about the middle of the third (first free) thoracic somite. The eyes are large, about half the length of the head, reniform in shape and containing black pigment. Each of the third to the seventh thoracic somites has its posterior margin produced into a median dorsal spiniform process; those of the third, fourth and fifth somites are larger than those of the following somites, but are smaller than the corresponding pro- cess of the head: these processes are not so well developed in the
. Fig. 9. Serolis exigua, Nordenstam, (J : x 12. keel which is continued backwards as a spiniform process to about the middle of the third (first free) thoracic somite. The eyes are large, about half the length of the head, reniform in shape and containing black pigment. Each of the third to the seventh thoracic somites has its posterior margin produced into a median dorsal spiniform process; those of the third, fourth and fifth somites are larger than those of the following somites, but are smaller than the corresponding pro- cess of the head: these processes are not so well developed in the female. The coxal plates of the third to the seventh thoracic somites are well developed, those of the third, fourth and fifth are separated from their respective somites by sutures. In the male the coxal plates of the seventh thoracic somite do not extend backwards quite as far as the pleural plates of the second abdominal segment; in the female they are considerably shorter. The abdomen (Fig. 9) consists of three free segments and a large terminal one; each of the three free segments is slightly keeled and has a short median dorsal spine corre- sponding with those of the thoracic somites. The pleural plates of the third abdominal segment extend backwards beyond those of the second to a point level with the base of the uropod; the outer margins of both the coxal and pleural plates are sparsely fringed with hairs and short hairs are also present on their posterior margins. The terminal segment is roughly five-sided, with the angles rounded. A median dorsal keel extends to the posterior extremity of the segment, but is more pronounced in the anterior half. On either side of this keel, lying midway between it and the lateral margin of the segment, is a lateral carina which extends nearly to the posterior margin of the segment; a secondary carina arises half-way along each of the lateral carinae and passes forwards and outwards to the lateral margin of the segment. The antennule (
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Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
