Skeleton in Corallium, Tubipora, and Syringopora. 33 
present in Zubipora. These latter structures, which are evi- 
dently very variable, I have not succeeded in detecting, but I 
do not doubt their existence. I cannot, however, admit that 
the presence of flat tabule in Zwubipora affords any strong 
argument for concluding that this genus is nearly related 
either to Syringopora or to any of the Favositide. Nor, 
indeed, can I admit that tabule, in themselves, are any guide 
whatever to the zoological position of any calcareous skeleton, 
whether recent or extinct, since these structures are known to 
occur in Zoantharians (Pocillopora &e.), Alcyonarians (Helio- 
pora), Hydrozoa (Millepora), and Polyzoa (Heteropora). I 
cannot, further, allow Mr. Hickson’s statement (loc. ct. p. 21), 
that “tabule are quite unknown amongst the Poritide,”’ to 
pass without pointing out that, in making it, he has fallen 
into error. Thus Dana, long ago, showed that “ tabule,” 
essentially similar to the tabule of Favosites, occur in the 
genus Alveopora, and figures of these were given by this dis- 
\" 
Part of a longitudinal section of the corallites of Porites clavaria, Lam. 
(Recent), enlarged eleven times. ¢, tabula; ss, septal spines, cut across near 
their bases; p, septal spine, projecting into the visceral chamber; ™, 
mural pore. 
tinguished observer in support of his statement. It is, more- 
over, easy to demonstrate by means of thin sections that 
“ tabula,” in all essential points quite like those of the l’avo- 
Ann. & Mag. N. Hist. Ser. 5. Vol. xiii. 3 
