218 
THE VOYAGE OF H.M.S. CHALLENGER. 
PLATE VIII. 
Fic. 1. Shows the structure of the soft parts of Astylus subviridis. A single cyelo- 
(=) 
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 
ceenosarcal canals occupying the axis of the branch are seen passing right 
and left. These place the cyclo-system in connection 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 sae (A). 
The base of the gastrozooid is rounded and basin-shaped. Large canals 
spring from the margin of the basin to join the ccenosarcal meshwork, and 
carry into the general circulation the products of digestion, but none such 
arise from the direct under surface of the zooid. 
GZ. Cavity of the upper chamber of the sac of the gastrozooid. 
GZ. Cavity of the lower chamber of the sac of the gastrozooid. 
Z. The gastrozooid. 
O. 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. 
DZ, DZ. Dactylozooids retracted mto their pores, and doubled down 
into the mouth of the sac of the gastrozooid. 
P, P. Mouths of the sacs of the dactylozooids, occupying in the recent 
condition the dactylopores. These mouths are in this species 
elongate in outline, and simulate the interseptal spaces of Anthozoan 
corals. 
G, G. Male gonophores in special sacs, and springing from branches of 
the ccenosarcal network. 
©. Deep axial ccenosarcal canals of the branches of the coral on which 
the cyclo-systems rest. 
8, 8. Superficial networks of finer canals lying immediately beneath the 
superficial external layer of the ectoderm. 
R, R. Radially disposed offsets of the coenosarcal network springing from 
the sac of the gastrozooid. 
X, X. Inter-radial spaces (cf Pl. VI. R R, X X). 
