REPORT ON THE REEF-CORALS. 81 
series in the more central parts of the colony are found to be united. A careful 
examination shews, however, that this union is altogether a secondary process, arising not 
with the original development of the series, but later on, when, by their increase in 
size, their adjoining edges have been brought into contact at many points and have then 
coalesced, as it were, for want of space. This process of union can be directly traced in 
large specimens ; and, in these, ample confirmation will be found in the presence of the 
larger or smaller openings of variable shape which have been left in many places where 
complete union has not yet taken place between neighbouring series. Towards the 
central parts of these large specimens, where the union due to this secondary process is 
most complete, the resulting ridges have all the superficial characters of the normally 
developed ridges of Symphyllia, with the exception that their course is often interrupted 
by the occurrence of the variable-sized apertures, which in some cases will be found to be 
extremely small or even on the point of being obliterated. The peripheral portions of 
all such colonies, moreover, shew clearly the normal Mussa growth. 
The characters which separate Jsophyllia, are discussed under that genus. 
Two species of Symphyllia are in the collection. 
1. Symphyllia sinuosa (Quoy and Gaimard). 
Meandrina stnuosa, Quoy and Gaimard, Voy. de l’Astrol., Zooph., p. 227, pl. xviii. figs. 4, 5. 
_ Symphyllia sinuosa, Milne-Edwards and Haime, Ann. d. Sci. Nat., ser. 3, vol. x., pl. vill. fig. 7. 
Two small fragments were collected which seem referable to this species. The 
corallum is rather light and cellular, and the ridges are narrower and less rounded than is 
common in the species. 
Locality. Samboangan, Philippines. 
2. Symphyllia acuta, n. sp. (Pl. IIL. figs. 5-50). 
Corallum with the upper surface more or less flattened ; coste on the lower surface 
narrow and thin, denticulate. Walls simple throughout, leaving no furrow above, never 
much thickened, being about 2°5 to 3 mm. wide in a transverse section of the corallum. 
Calicinal series very irregular, often nearly straight, generally sinuous; two or more 
centres often placed in the breadth of the same valley, but always opposite the point of 
development of new ridges where the valleys are very wide. Width of the valleys from 
15 to 20 mm., depth from 10 to 15 mm. The ridges are very uniformly angular, broad 
below, and becoming quite narrow and acute above, never broad and rounded. Septa 
narrow, rather thin, numerous, and closely placed, from 12 to 15 per centimetre, generally 
alternately large and small, with unequally small and sharp teeth which are somewhat 
thicker and longer at the upper part, but never become large and stout. Columella 
(zoOL. CHALL, EXP.—PART XLVI.—1886.) Zz 11 
