INDIAN OCEAN PORITES. 213 
217. Porites Ceylon (9221. (P. Ceylonica prima et vicesima.) 
[Shore-reefs near Galle and Belligam, coll. Ernst Haeckel; Museum Zool. Inst., Jena. | 
Syn. Porites fragosa Ortmann, Zool. Jahrb. iv. (Syst.) (1889) p. 501. 
Description—tThe corallum rises from a broad, humpy base on a constricted stalk, the 
top of which flattens out, mushroom-like, into a round expanded disc, humpy and with 
indented contour. 
The calicles are 1 mm. across and flat; the walls are thick; the pali visible; but the 
columella (=central tubercle) obscure. 
This is again one of Dr. Ortmann’s descriptions. Unfortunately Dana’s description of 
his P. fragosa is very incomplete, and there is no evidence that the two are really alike. 
218. Porites Ceylon (9222. (P. Ceylonica secunda et vicesima.) 
[Shore-reefs near Galle and Belligam, coll. Ernst Haeckel; Museum Zool. Inst., Jena. | 
Syn. Porites cribripora Ortmann, Zool. Jahrb. iv. (Syst.) (1889) p. 501. 
Description.—The corallum is encrusting and humpy. 
The calicles are very small, hardly 0°5 mm. in diameter; the walls are blunt, but of 
variable thicknesses ; columella hardly visible. 
This is Dr. Ortmann’s description, but his identification overlooks the fact that Dana’s 
Porites cribripora from Fiji had calicles twice as large, and, as he himself notes, less crowded 
than is the case in this Ceylon form. We know little about the affinities of corals, and we 
shall not gain anything by assuming such distant forms to be closely related. 
MALDIVES. 
219. Porites Maldives (31. (P. Maldiviwm prima.) (Pl. XXXI. fig. 7.) 
[Maldives ; British Museum. ] 
Description—The corallum forms rounded irregular knobs, rising from loose fragments of 
corroded coral and calcareous alge. The surface is nearly smooth, and the living layer creeps 
down irregularly and is sometimes 6 em. deep. 
The calicles are 1 mm. in diameter, flush with the surface, and circular. The walls vary 
in thickness ; where thinnest they consist of a delicate, incomplete, membranous ridge slightly 
raised. This thickens as a very open filamentous reticulum, which extends either right to the 
top of the wall ridge or stops below it; it may either merely fill in the angles and make the 
ealicles circular, or the whole wall may be thickened. In all the ealicles with the thinnest walls 
