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Show 740 MR. J. STANLEY GARDINER ON [June 6, figure and the above description. The section of the theca, showing profile of septa, is the same as in Dana's figure, but the upper ends of the septa over the theca are generally more acute. The valleys vary greatly in depth and breadth, in accordance with the sinuosities of the surface of the colony. In breadth they vary up to 4 m m . by about the same in depth, being always markedly deeper than in m y specimen of Leptoria gracilis. The septa on the sides of the straight valleys distinctly alternate in size, the smaller not reaching the columella. Where the valleys are more sinuous the arrangement, however, is not so regular, and often 3-5 contiguous septa meet the columella. Tbe columella is very similar to that of Li. gracilis, but the lobes on the surface are much lower, broader, and less marked. Wakaya, Fiji; reef. I am very doubtful whether this species is really distinct from L. gracilis, as the differences might be almost explained as due to different food-conditions in the two localities, as in the specimens of Hydnophora microcona from Funafuti and Wakaya; there are, however, no intermediate forms, nor can intermediate calices be seen on the specimens. Genus CCELORIA. Cceloria, Milne-Edwards & Haime, Cor. ii. p. 411 (1857). Cceloria, Duncan, Rev. Madrep., Jour. Linn. Soc. xviii. p. 89 (1884). I have referred fifteen specimens to this genus, which is very doubtfully distinct from the genus Mceandrina. The chief difference, according to Martin Duncan, is that the columella in Mceandrina is " formed of masses of spongy tissue, well-developed," and in Cceloria " formed by trabeculae from the edges of the septa, may be spongy." If this view is correct, it implies that Mceandrina has a true columella, formed, as in Astroides calycularis, by a deposit on the batal plate, while in Cceloria tbe columella is a secondary formation. Such a question can be settled only by a study of the development, but in the adult colonies there does not appear to be any real difference between the columella of the two genera, except such as would necessarily follow from the rather deeper, less sinuous, and thinner-walled valleys in Cceloria. The theca is lormed in Cceloria by a thickening of the septal sides. This thickening in a single colony may be plate-like, or in the form of nodules joining tbe septa, later broadening and forming a continuous wall, or very narrow, the theca in this case being formed mainly by a deposit of corallum on its upper edge. There is hence no reason, as Duncan has supposed (Jour. Linn. Soc, Zool. xvii. p. 363, 1884), for the separation of the species C. pachychila Ehrenberg as the type of a new genus. The genus is very abundant on the lagoon-shoals at Funafuti, where it forms large, spreading masses, which vary in colour from brown to green. It is also found sparingly on the leeward reefs at |