168 MADREPORARIA, 
symmetry tend to close them up. The fossa is small and deep, with only faint traces of a 
tubercle far below the surface. 
The aspect of the coral is soft and woolly. The vertical section shows trabecular and 
horizontal elements about equally developed, large rounded pores, and a slight tendency for 
the whole to melt down into a flaky reticulum. 
The colour is a rich reddish-brown. 
This beautiful coenenchymatous Porites, with its tendency to melt down into a flaky 
reticulum, is interesting in association with the next form, in which the reticulum has been 
dissolved into a system of horizontal flakes. There are several quite different forms of ccenen- 
chymatous Porites in this China Sea group. 
Some of the warts seem to be due to the presence of Balanids, but cenenchymatous papill 
may be seen rising without any visible cause. 
a. Zool. Dept. 93. 9. 1. 77. 
167, Porites China Sea 94. (P. Sinensis quarta.) (Pl. XXVL. figs. 1, 2,3; 
Pl. XXXYV. fig. 9.) 
[Macclesfield Bank, 23-40 fathoms, coll. Bassett-Smith ; British Museum. | 
Description.—The corallum is explanate, thin, with smooth, level or slightly wavy surface. 
Old stocks may consist of a series of flat dises increasing in size one above the other, and with 
free edges which are thin, 1 mm., and sharp; their central regions are about 5 mm. thick. 
The calicles are large, 1:5 mm., ill-defined, visible to the naked eye on unbleached 
specimens owing to the presence of dried dead matter ; on bleached specimens only discover- 
able with a pocket lens. The walls are flat, variable, sometimes 1+5 mm. in width. They are 
built of flat flakes with raised, slightly curling edges, but typically without surface granules, 
which would indicate the presence of trabecule ; with few, and those very small, perforations 
through the flakes. These wall flakes invade the calicle and entirely obscure the radial 
symmetry. No definite formule can be seen in septa or pali. A few curling points to 
irregular septal tongues represent the pali. 
The vertical section (Pl. XXVI. fig. 2) typically shows a loose open reticulum built up 
of wavy horizontal elements, with no clear traces of continuous trabecule. 
The colour of the unbleached coral is a rich light brown. 
This coral is one of the most remarkable in the whole group, because it shows an extreme 
specialisation of the horizontal elements with obscuration of the vertical trabecular elements. 
It is especially remarkable because a Goniopora occurs in the same locality and at about the 
same depth, which shows a similar structural differentiation, and is of the same colour. Thus 
forms of two distinct genera have acquired almost identical characters in the same locality— 
though they retain their generic distinction. This is the more interesting because in each case 
their characters are among the most striking yet known in their respective groups ; indeed, 
only the wide oversight of the range of possible forms which the Museum collection affords 
