MADREPORARIA WHITELBGGB. 357 



Radial corallites extremely variable in shape and in distance 

 apart. On the lower parts of the main branches they are distant 

 and deeply immersed ; in the angles between the branchlets they 

 are crowded, immersed, or slightly verruciform ; on the lower 

 two-thirds of the branchlets they are appressed, half tubular, and 

 have the apertures directed upwards. 



The clustered radials at the summits of the branchlets are im- 

 mersed or subimmersed, passing through shallow nest-shaped to 

 beak-nariform, with an elongated aperture. They are so irregularly 

 heaped together that the axial corallites become obscured. The 

 largest are about 3 mm. in length and 2 '5 mm. in diameter. 



There are twelve well developed septa. The primaries and also 

 the directives in the elongate forms are broad and frequently meet 

 below. 



The surface, including the corallite walls is closely echinulate. 

 The echinulse consist of flat plates, often denticulated and wid^r 

 at the apex than at the base. They are about (H2 mm. apart. 



Reefs in the lagoon. 



MADREPORA PATULA, Brook. 



Madrepora patula, Brook, Cat. Madr. Corals, Brit. Mus., i., 1893, 

 p. Ill, pi. ix., fig. E. 



One fine example of this species in the collection. 

 Reefs in the lagoon. 



MADREPORA EFFLORESCENS, Dana. 



Madrepora efflorescens, Dana, Zoophytes, U.S. Explor. Exped., p. 

 441, pi. xxxiii., fig. 6. 



A young specimen, referable to this species, was obtained in 

 the lagoon. 



The base is incrusting, and forms a discoidal expansion 12 cm. 

 in diameter. At the origin of the pedicel it is 2 cm. thick, 

 thinning down to 2 or 3 mm. at the margin. The pedicel is 6 

 cm. in diameter, and 2 cm. in height. The branches number 

 between forty and fifty ; inferiorly they are all more or less 

 fused, superiorly their apices are free ; about 1 cm. in height and 

 pretty regularly the same distance apart at the apex. Their 

 diameters range between 5 and 10 mm. 



The corallites on the expanded base are nariform or tubo- 

 nariform, with numerous immersed ones between. They are 2 

 mm. in diameter, the same or less in height, and about 2 -5 mm. 

 apart. The outer wall is more or less wanting. 



The corallites on the pedicel and the lower parts of the branches 

 are longer, stouter, and farther apart than those on the base. The 



