490 MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLASTERIDHD. 
tinuations of the dactyloj^ores appear as a circlet of circular openings at 
the bottoms of the wide pseudo -interseptal spaces. The gastropore has 
two mouths, an upper circular and wider one, and a deeper constricted 
opening, which is rendered horseshoe-shaped by the projecting tongue of 
calcareous matter B. 
Fig. 1G. Distichopora coccinea. The pores are entirely confined to the central lines 
of the sides of the branches of the flabelliform coral. The pores here occur 
in regular straight rows. The gastropores form a median row, and on 
each side of this is a single row of dactylopores, the mouths of which are 
elongate in form with their longer axes directed towards the gastropores. 
PLATE 3 G. 
Section vertical to the external surface of the decalcified living lamina of Spora- 
dopora dichotoma. 
The main mass is seen to be composed of a network of ramifying and freely 
anastomosing canals. The canals are of larger diameter towards the base of the 
section, where they are continuous with the body cavities of the zooids; but in the 
most inferior region they are again smaller, being here somewhat atrophied and effete. 
Towards the outer surface of the coral the canals are of smaller diameter and enclose 
smaller interspaces than the larger deeper canals. The interspaces throughout the 
meshwork are, in the recent condition of the coral, filled by the calcareous corallum. 
Lying in special cavities of the meshwork are seen a gastrozooid and two dactylo- 
zooids in the retracted condition, together with two sets of male gonopliores and three 
nematophores. The calcareous style of the gastrozooid is introduced in order to show 
the position which it occupies in the retracted condition of the zooid. 
G Z. External opening of the sac of a retracted gastrozooid. 
O. Mouth of the gastrozooid. 
S. Gastric cavity lined in its upper part by large elongate ovoid gastric cells ; in its 
lower, by ordinary endoderm cells. 
T. One of the tentacles of the zooid, of which a pair are seen in section. 
M. Longitudinal muscular layer of the zooid. The muscles are continued down on to 
the four main ccenosarcal canals leading from the base of the zooid. 
E. Ectoderm layer of the zooid. 
C. Cavity of one of the four large canals into which the zooid cavity divides at its 
base in order to become continuous with the canal system of the coenosarc. 
This canal is here shown as cut open, and is seen to be lined with endo- 
derm cells, the layer of which is continuous with that lining the zooid 
cavity. 
S'. The calcareous style, here introduced to show the position which it occupies 
