REPORT ON CORALS—HYDROCORALLIN 2. 93 
1. Millepora, Linneeus (Syst. Nat., ed. 10, t. i. p. 790, 1858). 
Genus with the characters of the family. 
2. Family SryLasTerip&, Gray. 
Coenosteum arborescent, with a strong tendency to assume a flabellar form, and to the 
development of the zooid pores on one face only of the flabellum, or on the lateral 
margins of the branches composing it. In some genera a superficial layer only of 
the coral is living ; 
with tabule in two genera only. Gastropores usually provided with a conical 
in others, nearly the entire mass retains its vitality. Pores 
calcareous projection, “style,” at their bases. In some genera a rudimentary style 
present in the dactylopores. Pores scattered irregularly, or grouped into more or 
less symmetrical systems, composed of a centrally-placed gastropore surrounded by 
a circlet of dactylopores. In some genera the mouths of the dactylopores appear as 
elongated chambers, disposed radially round the centre of the gastropore into which 
they open, and the chambers being separated from one another only by thin partitions, 
“‘ nseudosepta” ; the systems, “ cyclo-systems,” simulate closely the calicles of Hexactinian 
corals. Nematocysts of two kinds, large and small, and of uniform shape in all the 
genera, Three-spined nematocysts absent. Gastrozooids cylindrical or flask-shaped 
in form, always entirely retracted within the gastropores when at rest; those of the 
former shape with from four to twelve tentacles, set in one whorl, and regular in 
number in all the gastrozooids in each species ; those of the latter devoid of tentacles. 
Dactylozooids simple elongate-conical bodies, devoid of tentacles, sometimes capable 
of entire retraction within the pores, sometimes not. Stocks of distinct sexes. Gono- 
phores adelocodonic, developed within sacs, “gonangia,” which are contained within 
special cavities in the substance of the ccenosteum, “ampullz.” Stocks of the two sexes 
alike in form as far as known, except in the size of the ampulle, which are larger and 
more prominent in the females. Ampulle containing in male stocks several gono- 
phores ; in female, in some genera, a single gonophore, in others several. Spadix, in 
the female gonophores, cup-shaped, embracing a single ovum only, which becomes 
developed into a planula within the gonangium. 
1. Sporadopora, Moseley (Phil. Trans. Roy. Soc., 1878, part 2, p. 474) = Polypora, 
Moseley (Proc. Roy. Soc., No. 172, 1876, pp. 94, 95). 
— Ccenosteum pure white, composed of finely reticular but compact ccenenchym, forming 
stout vertical stems, usually compressed from before backwards, so as to be oval in trans- 
verse section. Stem giving off a limited number of irregularly dichotomous branches, 
which are flattened like it, and tend to coalesce by their lateral margins and assume a 
flabellate form, which is sometimes somewhat curved. Surface of the ccenosteum 
