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Show 414 PROF. J. A. THOMSON AND MR. W. D. HENDERSON ON [Apr. 10, As this seems to be a variable sjjecies, we add a few notes in regard to other specimens '.- (a) The colour of some when alive was blue all over; the colour of the preserved specimens may show a tint of green or may be pure white. (/>) The size of the larger zooids is variable, e.g. in length and breadth in millims. 20 x 2*5, 15 x 2, 7 x 1*5. (c) N o importance need be attached to cases where there seem to be five pinnules abreast on one side of a tentacle, since these trivial deviations occur in colonies where the normal number of four rows is thoroughly dominant. (d) Another set of specimens was marked by the following peculiarities: (1) Somewhat slender stalks, 17-25 m m . in height, rise from a flat spreading membrane. (2) The pinnules, which are mostly absent, seem to have been decidedly shorter than the normal, a deviation which is also noted by May; but it is difficult to say how much of this is purely artificial. (3) The calcareous bodies mentioned by Kolliker, but not found by May, are abundant. They are either spherical or roundish oval in shape and highly refractive, with a diameter of about 0*001 mm. Some yellowish spherical zoochlorella}, about 0*36 mm. in diameter, are also present. Loccdity. Zanzibar Harbour, lowest tide-level. CESPITULARIA COSRULEA May. (1) A much-branched colony which was, when alive, of "a brilliant sea-green colour, except the upper faces of the small zooids which were brown." It seems to be referable to May's Cespitularia ccerulea, which is described, howTever, as " flesh-coloured with a tinge of bright blue." This specimen agrees with May's diagnosis in having (1) One row of pinnules on each side of the tentacles ; (2) Polyp-bodies about 4 m m . in length ; (3) Tentacles about 2*5 m m . in length ; (4) N o calcareous bodies. The mode of branching, on the whole, corresponds with May's description ; but there is this noteworthy peculiarity, that one division of the colony is sometimes connected with the main mass by a narrow isthmus, e.g. 10 m m . in length by 1 m m . in breadth. (2) Another colony rises from a flattened base which spreads over a part of the surface of a shell, the rest being covered by a sponge. When alive it was described as having "pink stems with slender brown zooids." The preserved specimen had at first a greenish tinge, which was afterwards .replaced by the usual dull creamy white. The stalk, which soon branches, is fairly firm in texture, but there are no calcareous corpuscles. Near the base it gives off a small branch which has spread over |