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Show 1903.] MEDUS.E FROM BRITISH COLUMBIA AND ALASKA. 171 well-marked unbranched lateral diverticula. These diverticula are absent on the upper margin of the circular canal, and are thus unlike the condition described in Catablema by Haeckel. Colour.-Bell bluish throughout; tentacles, gonads, and stomach dark red or purplish. Habitat.-St. Paul Island, Pribyloff Islands, collected by Kincaid. Discussion.-The large number of tentacles in double rows and the opposite position of the diverticula of the stomach, bearing gonads, are the reasons for placing this form under Turris. It is true that the stomach and gonads are small for Turris, but the size of these organs is variable. Beyond these considerations this form seems to resemble more Tiara pileata than any species of Turris. It differs from Turris digitcdis in the smaller apical process, the size of the gonads, the shape of the radial canals, and the length of the manubrium ; from T. neglecta in the shape of the stomach which is not cubical, in the regular opposition of gonad-pouches, and in the number of tentacles. The specific characters are :- the short conical apex, the large number of tentacles (140), arranged in two rows, the spindle-shaped radial canals having simple lateral diverticula throughout their length, the five or more pairs of gonadial pouches from each of the four stomach-lobes, the small size of these and the stomach ; in these respects it approaches the condition in Tiara,, and, lastly, in its size. Turris digitalis, the original Medusa digitate of Fabricius, is remarkable for its extensive distribution in northern waters; it is probable that Turris neglecta will be found to have a similar distribution. Four out of the seven genera of Haeckel's subfamily Pandaeida? have been reported from arctic waters. III. MARGELID^E Haeckel. HIPPOCRENE Mertens. 1. HIPPOCRENE MERTENSII (Haeckel, 18, p. 92). Synonym Bougainvillia mertensii Agassiz. Specific desertion.-The bell is nearly spherical, somewhat flattened, and contracted at its four meridional points, having thus a cubical appearance, 5 m m . by 4 m m . The velum is well developed. The oral tentacles are situated at the upper end of the proboscis--two large, one small, and one rudimentary : this last being due possibly to imperfect preservation or an abnormality of the specimen. There is a marked inequality of the tentacles and the tentacle-bulbs. The former are stout, branched at the base, each branch dividing dichotomously about six times. Two of the tentacle-bulbs are large, horseshoe-shaped, and twice as broad as the proboscis. Each bears twenty-one tentacles and as many eye-spots. The other tentacle-bulbs could not be |
