| OCR Text |
Show 754 MR. J. STANLEY GARDINER ON [June 6, exotheca. The valleys between tbe calices are always distinct and usually about 3 m m . broad. They are not closed in below by a dense, smooth peritheca as represented in Milne-Edwards and Haime's figure, but at the bottom the costae of neighbouring calices meet. The columella is situated about 1*5 m m . below the crown of paliform teeth, the whole calice being 4-5 m m . deep. Rotuma ; reef. 5. ORBICELLA CURTA Dana. Orbicella curta, Dana, Zooph. p. 209, pl. x. fig. 3 (1846). There is in this species always a distinct valley between the calices, but the interthecal spaces are often filled up with dense solid exotheca. The calices have typically 48 septa in four cycles, but usually the last cycle is incomplete. The first and second cycles meet the columella; the primaries are much coarser than the rest, ending above in broad (1*5 m m . ) , slightly more exsert edges, and below having generally small paliform teeth. Tbe rest of the septa are very thin and equally exsert with finely toothed edges. The tertiaries often bend round and fuse with the secondaries before the latter join the columella; the quaternaries are always distinct but very narrow. The costae are of equal thickness and meet in tbe valleys, but are not directly continuous between the calices. The columella is small and formed by twisted lamellae from the septal edges, which have from the surface rather a papillate appearance. The calices in m y specimen are rather irregular and a few exhibit well-marked fissiparity. The largest are from 8-9 m m . in diameter by 5 m m . deep. Funafuti; one specimen. 6. ORBICELLA CORONATA Dana. Orbicella coronata, Dana, Zooph. p. 211, pl. x. fig. 4 (1848). There is one specimen of this species, which possesses very markedly the specific characters given by Dana. The calices are crowded, but have nearly always distinct rims ; the costae, however, are sometimes continuous from calice to calice. The septa form three cycles, of which the primaries are considerably (1 mm.) more exsert than the secondaries and the latter than the tertiaries. The costae also show similar differences. The primaries have almost horizontal upper edges, 2 m m . broad, and distinct, small, low, paliform teeth. A few of the secondaries may meet the columella, but generally they are little broader than the tertiaries. The sides of all the septa are coarsely granular and the edges of all end in fine, subequal spines. The columella is very small and formed by a few flat trabeculae from the primary septa. The calices vary up to about 8 m m . in diameter by 4 m m . deep. The primary septa are about 2 m m . exsert. Funafuti; leeward reef. |
