INDIAN OCEAN PORITES. 211 
The coral presents a very striking variation on those forms of the genus which have walls 
of a flaky reticulum, the septa being smooth and thin. It is not only interesting on that 
account, but because its surface characters are not unlike those of the coral called by Esper 
Madrepora punctata (Suppl. i. (1797) p. 86, pl. Ixx.). That coral was, however, from the 
Moluccas, so that it is safer to describe this one separately. Esper’s name has already been 
applied too freely to different corals (see under P. Moluccas 1, p. 161) some of which are 
certainly entirely different. 
a. Zool. Dept. 83. 3. 24. 2. 
213. Porites Ceylon (9917. (P. Ceylonica septimadecima.) 
[Galle, coll. Dr. Ondaatje; British Museum. ] 
Syn. Porites echinulata Ridley, Ann. and Mag. Nat, Hist. xi. (1889) p. 258. 
This was a Porites recorded by Mr. Ridley from Ceylon and not described, apparently 
because it so closely resembled the Red Sea form called P. echinulata by Dr. Klunzinger (see 
P. Red Sea 7, p. 241). I have not been able to examine the specimen. 
214, Porites Ceylon (9918. (P. Ceylonica octavadecima.) (Pl. XXXI. fig. 6.) 
[Galle, coll. Dr. Ondaatje ; British Museum. | 
Syn. Porites Gaimardi Ridley, Ann. and Mag. Nat. Hist. xi. (1883) p. 258. 
Description.—The corallum is massive, with slightly convex top, which is everywhere 
raised into a number of small, rounded waves. 
The calicles are shallow, variable in size up to 1°25 mm. and sub-circular on the tops of 
the waves, small and angular in the narrow valleys. The walls are uniformly low, sharp, 
membranous ridges, seldom perforated, slightly wavy, with smooth but uneven edges, that is 
here a little taller, there a little shorter, sometimes rising into points at the angles. The septa 
begin below the edges of the walls; they are thin, wavy, and with irregular swellings ; near the 
walls they sometimes form a second inner synapticular ring, or themselves fork, especially 
where an angle in the wall between it and the inner circle of the calicle skeleton has to be 
filled up. They usually meet a partial or complete columellar ring which is very thin 
and filamentous. An imperfect ring of paliform rods rises from this circle, but they are not 
conspicuous, and never reach to the top level of the wall. The triplet is trident-shaped, and 
the small central tubercle is flattened in the directive plane. The skeletal elements, viz. the 
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