CORALS FROM MURRAY, COCOS-KEELING, AND FANNING ISLANDS. I95 



Calices shallow; diameter, measured between mural summits, 1 to 1.5 mm.; about 

 7 calices in a distance of I cm. 



Walls usually straight, rarely zigzag, composed of vertical trabecule joined by synap- 

 ticulas into a ring. The trabeculse terminate in prominent rough granulate mural denticles, 

 of which there are about twice as many as there are septa. The denticles, when extended, 

 are parallel to the septal planes. The granulations divergent. 



Septa 1 2 in number, rather thick, intefseptal loculi usually narrower than the septa, the 

 restriction mostly due to the relatively large septal granulations. Usually two synapticular 

 rings within each calice. Above the outer ring is a ring of irregularly shaped, granulate 

 septal denticles. Between these and the wall the outer ends of the septa are usually bifur- 

 cate, each limb of the fork corresponding to a mural denticle. The inner synapticular 

 ring corresponds in position to the pali. The palar formula is normally complete, i. e., one 

 on the solitary directive, one on each member of the triplet, rarely with suggestions of trident 

 formation, and one at the fusion of the lateral pairs. Those before the lateral pairs are 

 the more prominent; they are tall, reaching almost to the level of the upper edge of the wall, 

 erect, slender, and roughly granulate. The other pali are lower and smaller. The directive 

 of the triplet is usually shorter than the lateral members, and the palus on it stands back 

 slightly. Between the palar trabecular and the outer septal denticle an intermediate 

 denticle is usually on each member of the lateral pairs and sometimes on the solitary directive 

 and each member of the directive triplet. The single septal denticle or the outer one, 

 where two are present, is only slightly detached from the wall. 



In places the outer synapticular ring is highly developed and the mural trabecular 

 thickened, thus producing the appearance of a rather wide, reticulate wall. 



The columella is an erect, narrow plate, roughly granulate, joined to the septal ends 

 by radii, frequently 5 in number, between which the spaces are narrow but open. 



The preceding description, except of the growth-form, is based on one specimen 

 (see plate 85, figs. 4, 4a). The principal variations within the colony consist in the 

 degree of the development of the outer synapticular ring and whether the outer 

 septal denticles are below or flush with the upper edge of the wall, producing 

 respectively the appearance of narrow, simple walls or of wide, reticular walls. 

 It may be added of the aspect of the corallum that under a binocular microscope 

 the texture is coarse; the granulations are greatly developed and restrict the inter- 

 septal and other spaces. 



Stations, Murray Island. — Southeast reef flat, line I: 



450 feet from shore; water about 6 inches deep. 



550 feet from shore; water about 8 inches deep; coral sandy bottom. 



620 feet from shore; water 10 inches deep at low tide; bottom sandy (type specimen, 

 see plate 85, figs. 4, 4a). 



675 to 720 feet from shore; water 12 inches deep. 



800 feet from shore; water about 11 inches deep; hard, rocky bottom. 

 1,000 feet from shore; water about 15 inches deep; bottom hard rock with some sand. 

 1,200 feet from shore; water about 9 inches deep; rocky bottom. 

 1,400 feet from shore; water 14 inches deep; hard, rocky bottom. 

 Lithothamnion ridge, 1,720 to 1,775 f eet f rom shore. 



The variation in form was noted in the first sentence of the description, and 

 most of the other variation is shown on the described specimen. On the specimens 

 1,200 feet from shore some of the calices near the lower edge are 2 mm. in diameter 

 (plate 85, fig. 5), and the intervening walls are raised and thin, but the calices are 

 shallow. On top of the corallum the calices are 1.5 mm. in diameter. A specimen 

 (plate 85, figs. 6, 6a), 800 feet from shore, has calices frequently slightly less than 

 1 mm. in diameter; the walls usually are simple, but in places are reticular, espe- 

 cially in the angles; and the columellar tubercle is less prominent than on the average 

 in other specimens. Notwithstanding the variations noted, the essential characters 

 are uniform. As they are expressed in the description they will not be summarized. 



Bernard's Porites Great Barrier Reef (42)34 almost certainly also belongs to this 

 species, and perhaps other morphologic variations described by him. 



