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Show 1903.] MARINE FAUNA OF ZANZIBAR. 135 Thus, though in the majority of cases the disappearance of hooked setae and the change in the character of the ventral cirrus are coincident with the appearance of the first gill, exceptions are proportionately numerous, so that variations of these characters cannot well be made the ground for systematic distinctions. Genus O N U P H I S. O N U P H I S H O L O B R A N C H I A T A Marenzeller. (Plate XIV. fig. 2.) Five specimens were collected, and in all the hind end was missing. The largest fragment is very nearly of the same size as that described by Marenzeller from Japan, viz. 4 cm. x 0*3 cm., and consists of nearly the same number of segments, 85. This, with three others about half the size, was dredged from 10 fathoms in Wasin Harbour; the fifth, still smaller, being from the shore in the same locality. This last specimen is abnormal in having no gills on the first two pairs of feet. The coloration of the living animal is characteristic, the pattern on its dorsal surface serving to distinguish it at a glance from any of the numerous small species of Eunicidae living in the same locality. The ground-colours are of a light flesh-tint ventrally and light yellow-brown dorsally, but the central part of the prostomium and a small round area in the middle of each segment are white. The upper surface, however, as far as the thirty-fifth segment, is largely covered by markings of a dark, rather purple - brown (Marenzeller's " Dunkelbraun - violett " suggests an almost blue colour, which is not that present in my specimens). These are most numerous and closely placed at the bases of the feet, with the exception of the first three. On either side of the white central marks are slender transverse lines, three pairs, one of long, two of short marks to each segment. To the naked eye the back appears marked by two pairs of longitudinal bands, the outermost darker and of definite zigzag shape, the inner which bound the median moniliform white stripe, lighter and less definite in outline. The former is omitted from the first four segments, and the latter also is irregular there. There are dark marks on the prostomium just behind the bases of the tentacles, the ringed portions of which are themselves lightly marked. The fig. 2, PI. XIV., shows this pigmentation, the peculiar proportionate lengths of the tentacles, cfec. In feet, setae, gills, and other characters m y specimens agree minutely with Marenzeller's. The former, like their gills, are white and somewhat dorsally directed. The mandibular plates differ slightly in shape from Marenzeller's figure, having, in the cutting-edge, one deep, instead of two shallow notches. EUNICIN^E. Genus MARPHYSA. The following table, which includes all the species of which |