240 A. E. Verrill— The Bermuda Islands; Coral Reefs. 
Porites astreoides Lam. Figures 96, 96a. Plate xxix, fig. 1. 
Madrepora porites (pars) Pallas, Elench. Zoéph., p. 324, 1766. 
Porites astreoides Lam., Hist. Anim. sans Vert., ed. 1, ii, p. 269, 1816. 
Porites astreoides Dana, Zoéph. U.S. Expl. Exp., p. 561, 1846. Verrill, Bull. 
Mus. Comp. Zodl., i, p. 42, 1864. Pourtalés, Florida Reefs, pl. xvi, figs. 
1-12, 1880. Duerden, Mem. Nat. Acad. Sci., viii, pp. 550-552, pl. iii-v, 
figs. 28-42, 1902, anatomy. 
Porites astreoides Vaughan, op. cit., p. 317, plates xxxii-xxxiv, 1901. Verrill, 
these Trans., xi, pp. 160, 181, pl. xxxi, figs. 4, 4a, 1901. 
This coral is one of the most important of the reef-building corals. 
It forms large hemispherical, subglobular, or dome shaped masses 
when well grown, on the outer reefs, but is often found in the form 
of thick crusts. Its surface is generally more or less uneven or 
nodular. It sometimes becomes 2 feet or more in diameter, but is 
more commonly not more than 6 to 10 inches in diameter. 
Sil 96 
Figure 96.—Porites astreoides. Polyps in partial expansion, much enlarged. 
From colored drawing by A. H. V. 
Figure 97.— Porites porites, var. clavaria. One of the polyps fully expanded, 
Much enlarged. From life by the author. 
In life its color is usually greenish yellow, sometimes pale ocher- 
yellow, yellowish green or yellowish brown.” Duerden describes it 
as sometimes blue. 
The polyps, in contraction, are usually brighter yellow than the 
eeenenchyma ; when fully expanded they rise considerably above 
the coral and have twelve small blunt tentacles. The small mouth 
is bordered with white, and usually there are twelve thin white 
radial lines on the disk. The tentacles are sometimes whitish or 
very pale yellow, in other cases brownish yellow. Twelve small 
white specks often surround the base of each polyp. They usually 
stand so close together that when fully expanded the tentacles inter- 
lock and entirely conceal the surface of the coral. Occasionally 
