774 J. STANLEY GARDINER. 



spined ridges between the larger ; more than half of IV. is seldom present. The teeth of 

 all are rough, low, saw-like but not crowded, rather irregular. The columella is formed of 

 flattened trabeculae from septa I. and II. 



Locality. (1) A flattened mass 8'.5 x 3 cm. by 4 cm. thick, Minikoi, coral flat near 

 Wiringili ; (2) a similar mass 14 x 12 cm. by 4 cm. thick, Suvadiva, 40/; (3) a flattened 

 piece of a colony, deformed with barnacles and worms, 7x6 cm., with smoother septa and 

 rather deeper calices, and with endotheca more solid, Suvadiva, 20/; (4) a flat, thin, rough, 

 little colony with wavy epitheca underneath, 4x4 cm., quite similar to 1 and 2 but rougher 

 in appearance owing to the longer septal teeth, cycle IV. larger and more regular, often 

 cycles fusing, columella relatively larger, South Male, 30 / 



XIV. Genus Orhicella. 



I must still assert my inability to find characters which clearly sejmrate Plesiastraea 

 and Leptastraea from this genus (P.Z.S. 1899, p. 751). Generic characters ai-e presumably 

 more ancient than specific, or at any rate have become absolutely fixed. Such may be 

 crystallising between the three genera, but at present the process is quite incomplete. 



Distribution. The genus has two very common reef-species, 0. ehrenbergana and 

 transversa, capable of living absolutely under the breakers where also 0. annuligera dwells. 

 0. laxa forms great masses on the lagoon shoals at Minikoi, where 0. minikoiensis is 

 very common in one small area. One specimen of the genus was dredged, but that from 

 4/ only. Colour invariably some shade of green. 



35. Orbicella annuligera Ed. and H.' (PL LXIII. iig. 32.) Ed. and H., ii. p. 471. 

 Astrea annularis Q. and G., Zooph. p. 210, PI. 17, figs. 17—18, 1833. 



Four specimens correspond in every respect with the above descriptions. The septa and 

 costae are rough and the latter thick, septal teeth very low except the innermost, which is 

 always paliform, thickened and pointed, the series forming a well-defined crown 1 — 2 mm. 

 above the columella. Ordinarily 12 fuse in the centre of the calice and have paliform lobes, 

 but in the larger corallites there may be 14 or 16, the increase entailing the presence of septa 

 of the fourth cycle. The cohiniella is dense, formed by trabeculae from the septa, which 

 often fuse even outside the level of the pali so that the latter may appear to arise from 

 its surface. The corallites vary up to 7'5 nun. in diameter and the calices to 4'5 mm. 



Locality. Minikoi, reef-flat, and Goidu, E. reef, breaker zone. The former specimens 

 have deeper calices, in some places a little distorted, and smoother septa and costae than 

 the latter. All are quite thin and small, mere living fragments, probably of once much larger 

 spreading masses. Colour a brilliant yellow all over. 



36. Orbicella minikoiensis, n. sp. (PI. LXIII. fig. 35.) 



Colony massivCj under the overhanging edges longitudinally ridged costae, no distinct 

 epitheca. Corallites, 11 — 14 mm. in diameter, almost flat, often somewhat distorted by the 

 intercalicinal budding. Calices generally round, 8 — 10 mm. in diameter, varying from flat to 



' I fully accept Vaiighan's synonymy of O. acropora, the limits of its variability. There is a close connection 



U.S. Fish CoinmisxioH lliilletin, vol. ii. p. 301, 1900. The between the two species, however, and one could have wished 



specimens identified by me from Eotuma are rather different that Vaughan, after having made certain of 0. acropora, 



from the present ones of annuligera, but scarcely exceed had redescribed it. 



