494 MR. H. 1ST. MOSELEY ON THE STRUCTURE OF THE STYLASTERIDtE. 
Z, Z. Gastrozooids situate one at the base of each cyclo-system. 
D Z, I) Z. Dactylozooids. G G. Male gonophores. 
N, N. Nematophores. 
A. Pteflection of the surface layer of the ectoderm forming the sac of the gastrozooid and 
lining the gastropore. The sac-wall is very thin and transparent. Curved 
lines crossing the dactylozooids transversely about their middles, in the 
central cyclo-system shown in the figure, mark the lower and innermost 
margins of the dactylozooid sacs, where these become continuous with the 
sac of the gastrozooid. In the cyclo-system shown on the left in the 
figure, the sac of the gastrozooid and the portions of the sacs of the 
dactylozooids fronting the gastropore are represented as removed, together 
with the superficial network of the ccenosarc immediately beneath them, 
in order to display the connexions of the deeper systems of large main canals 
which connects the zooids of the cyclo-system directly with one another. 
B, B. Spaces in this deeper system of main canals. 
PLATE 41. 
Fig. 1. Shows the structure of the soft parts of Astylus subviridis. A single cyclo- 
system, divided in half, together with portions of the branch on which it 
rests, is represented in the figure. At the lower part of the figure the large 
ccenosarcal canals occupying the axis of the branch are seen passing right 
and left. These place the cyclo-system in connexion with the other 
adjacent cyclo-systems on the branches of the coral. The gastrozooid, which 
is devoid of tentacles, is seen resting retracted at the bottom of its sac (A). 
The base of the gastrozooid is rounded and basin-shaped. Large canals 
spring from the margin of the basin to join the coenosarcal mesh work, and 
carry into the general circulation the products of digestion ; but none such 
arise from the direct under surface of the zooid. 
G Z. Cavity of the upper chamber of the sac of the gastrozooid. 
G Z'. Cavity of the lower chamber of the sac of the gastrozooid. 
Z. The gastrozooid. 
0. The mouth appearing as a crucial slit with symmetrically-arranged 
elongate gastric cells. 
B. Tongue-like process of the wall of the gastropore which projects 
forwards horizontally over the summit of the retracted gastrozooid 
at a point where there is a sudden constriction of the pore. The 
projection of the tongue forms the opening of the constriction into 
a horseshoe-shaped aperture. 
D Z, D Z. Dactylozooids retracted into their pores, and doubled down 
into the mouth of the sac of the gastrozooid. 
