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Show 304 MR. CYRIL CROSSLAND OX THE [Feb. 16, a most, important addition to my collection, since several species of all these groups were here met with for the first time. Some time later I came across specimens of this species at low springtide on the west shore of Puopo Islet, Kokotoni Harbour, Zanzibar. Here the tubes were attached at their bases to the flat rock, and were stiff enough to stand vertically upright even when the water had left them. Tubes were also dredged in Wasin Harbour, whence also come three much younger specimens, which show important differences from the full-grown ones previously collected. The openings of the tubes are arranged more or less alternately on either side as in E. tibictnct Ehl., but are less numerous and the tubes are straighter. The basal part of the tube is very like the fragment figured by Ehlers (I. c. Taf. 22. fig. 1), which shows well their characteristic texture and surface. Although the tube-wall is not thicker than ordinary brown paper and is free from foreign material, it is perfectly opaque and so tough and elastic that the tubes are cut or torn open with some difficulty. The colour of the animal in life is uniformly blood-red, except towards the hind end, where the body becomes blackish. The head is broad and the peristomial segment, as usual, cylindrical (PI. X X I . fig. 1), but immediately behind this the body flattens ventrally, and a little later dorsally also, becoming in section a narrow rectangle. A slight increase in breadth takes place for a centimetre or two behind the head, after which the body is parallel-sided for the greater part of its length, becoming narrower and more cylindrical towards the tail. The diagrammatic sections explain these changes (text-fig. 52). The segments are very short throughout, though the six following the head are longer than the rest (see fig. 1, PI. X X L ) . Text-fig. 52. b. c. d -7m.m.-\ f-6 mm)) ( j x 2. Diagrammatic sections of body of E. tubifex, sp. n. a. Just behind buccal segment. b. In region of glandular feet, i. e. about 24th segment. e. In the branchial region. d. Near hind end of body. The prostomium (PL XXI. fig. 1) is short and broad, deeply notched in front and covered by the anterior edge of the buccal segment behind. The short and thick tentacles are indistinctly ringed and have each a small thickened basal portion. The middle one is about twice as long as the prostomium, the next h5m.mA |
