| OCR Text |
Show 1899.] ASTR.EID CORALS FROM THE SOUTH PACIFIC. 755 7. ORBICELLA ROTUMANA, n. sp. (Plate XLIX. fig. 3.) Tbe corallum is an incrusting mass, covered underneath by a thin, dense epitheca. The calices are crowded, but have nearly always a distinct rim, the costae never being continuous between. The septa are nearly equally exsert and the costae are subequal in size. The septa form three complete cycles, and usually the greater number of septa of the fourth cycle are present. The primaries, as in 0. coronata and 0. curta, have broad (2 mm.), horizontal, upper edges and are provided with rather long paliform lobes, often rising for 2-2*5 m m . above the columella. A few of the secondary septa sometimes simulate the primaries, but usually they do not meet the columella. The tertiaries are always distinct, but the quaternaries are scarcely distinguishable within the calices All the septa are relatively thin (not differing greatly one from another in thickness) with smooth sides, and are often much fenestrated ; their edges are covered with long, thin, pointed spines, which commonly increase considerably in length towards the base of the calice. The columella is very small, appearing in many calices to be little more than the fusion of the edges of the primary septa. The calices are rather crowded and distorted, varying up to 9 m m . in diameter by 4r-5 m m . in depth. Rotuma ; boat-channel ('?). One specimen. This species is very closely allied to 0. coronata and 0. carta. The calices of the three specimens of these species in m y collection scarcely merge into one another in any way, nor did I find any intermediate forms in the British Museum. 0. rotumana differs from 0. curta in its distinct paliform lobes, long, spiny septal teeth, tertiary septa never fused to secondaries, and the latter often simulating the primaries. 0. coronata differs from both in its much coarser and thicker septa, which seldom form more than three complete cycles. 8. ORBICELLA EXUNZINGERI, n. sp. Leptastro?a ehrenbergana, Klunzinger, Die Korall. des R. Meeres, iii. p. 46, pl. vi. fig. 3 (1879). There are two specimens, which undoubtedly belong to the species which has been excellently described and figured by Klunzinger under the name of Leptastrcea ehrenbergana. This species cannot possibly be the species described by Milne-Edwards and Haime under that name, so that 1 propose to call it 0. klunzingeri. As m y specimens agree in nearly every respect with Klunzinger's description, there is no need for m e to recapitulate tbe specific characters. Klunzinger's figure shows considerable variation in the size of the calices. In my specimens on the highest points, nodules on the colony, some of the calices are 8-9 mm. in greatest width, while in some of the valleys they do not average more than 3 mm. In the latter position further the thecae of neighbouring calices are completely fused, but the costae are not continuous. Funafuti and Rotuma. |
