MALAYAN PORITES. 169 
enables us to recognise their systematic positions at all. This, I think, supplies us with 
a very strong argument in favour of the power of the environment in moulding the forms of 
animal life. 
There are five specimens in the National Collection which may be here grouped together ; 
they all show striking variations. 
a. Is a large flat shield-shaped disc, supported on a series of earlier smaller discs. The 
successive discs seem to start irregularly, a portion of the colony somewhere near the centre 
arching upwards suddenly in order apparently to surmount some foreign organism ; the edges 
of this rising portion grow outwards above the colony from which it sprang. 
a. 37 fathoms (Pl. XXXV. fig. 9). Zool. Dept. 92. 10. 17. 87. 
' B. Is a much smaller colony, showing traces only of some four to five earlier growths. 
The characteristic features are again shown very clearly. 
b. 30-40 fathoms (a note on the label describes the 
polyps as showing “a complete circle of twelve white Zool. Dept. 93. 9. 1. 74. 
tentacles.”) 
c,d. Two very minute and probably young colonies of the same. Both show the same 
essential structure as a and 6, but yet differ from both. They are thin, one of them extremely so, 
0-5 mm. In this thinner one, although it is nearly 3 em. long by 1°5 broad, there are only two 
layers of skeletal flakes above the epitheca, and the calicles are difficult to make out even with a 
pocket lens (Pl. XXVI. fig. 3). Im the thicker one there are six layers of flakes, and the 
calicles are easier to find. 
c, d. 23-40 fathoms. Zool. Dept. 1904. 10. 17. 41 and 42. 
e. Is a larger colony, 8 cm. long, and showing traces of some six previous growths, 
the youngest as small as c. This coral is remarkable as a kind of transition form. It 
has a similar habit, but its surface is granular, and its section, though showing an immense 
development of wavy horizontal elements, yet has distinct vertical trabecule which appear at 
the surface in the granules upon the wall flakes, in the distinct ring of pali, and in the 
columellar tubercle. The question may well arise as to the correctness of placing it here. 
We have no evidence which would justify us in dogmatising at all about its affinities. That it 
is a transition form leading from the usual arrangement with developed trabecule to this 
with purely horizontal elements is obvious, but in the face of the fact above described of 
representatives of two distinct genera becoming so alike under the influence of the environ- 
ment, we cannot tell but that this may be some entirely different Porites also being slowly 
modified in the same direction. 
e. 31 fathoms, Zool. Dept. 92. 10. 17. 95. 
There is also a bottle containing three small fragments in spirits, 40 fathoms. 
168. Porites China Sea ag. (P. Sinensis quinta.) (Pl. XXVL. fig. 4.) 
[Macclesfield Bank, 13 fathoms, coll. Bassett-Smith ; British Museum. |} 
Description.—The corallum is explanate and thin, and in struggles with other organisms 
seems to build up an irregular crust, with edges here free, there adhering, and with a surface 
Z 
