496 MR. H. N. MOSELEY ON THE STRUCTURE OP THE STYLASTERIDMt 
and the disposition of the several parts is here shown in detail. The breeding sac 
of this system is in an early stage of development. The dactylozooids are shown as 
protruded. 
In the cyclo-system on the right hand the superficial membrane is mostly left entire, 
and the cyclo-system is not opened, but a view is obtained into the open mouth of the 
gastropore showing the dactylozooids doubled down mto it. The breeding sac is here 
shown in its fullest activity, and containing a planula ready for emergence. The sac is 
represented as cut open in order to exhibit the contained structures. 
G Z. Cavity of the sac of the gastrozooid. 
O. Mouth of the gastrozooid, which is devoid of tentacles. 
S. Digestive cavity of the zooid lined with elongate gastric cells. 
M. Longitudinal muscular layer of the zooid. As in Astylus subviridis, numerous 
canals pass off from the margin of the rounded base of the zooid, but none 
from the under surface of the base itself. 
D Z, D Z. Dactylozooids. 
P, P. Mouths of the sacs of the dactylozooids. 
L, L. Peculiar protective laminse, or lids, folded in this genus in front of the openings 
of the cyclo-systems. In the case of the left hand system of the figure the 
ramifications of the superficial network of the coenosarc, prolonged into the 
body of the lid, are shown, and also the nematophores with which the lid 
is provided. In the other system represented, the superficial layer of the 
coenosarc is shown intact. The downward prolongation of the base of the 
lid, which should pass between the sac of the gastrozooid and its main 
upward canals, is omitted for clearness sake. 
N, N. Nematophores. One of these is situate at the outer margin of the cyclo -system 
in each interval between the sacs of the dactylozooids. 
G. Female gonophore contained, with two others in earlier stages, in a special brood- 
sac as yet not far advanced in development. 
G'. Brood-sac in full development containing ova and embryos in all stages of develop- 
ment. 
Ov, Ov'. Fertilized ova in advancing stages of development and cell multiplication. 
P 1. Early stage of planula embryo. The thin ectoderm appears as just differentiated. 
P 2. Planula fully advanced with more fully developed and thickened ectoderm. 
P 3. Fully developed planula with highly differentiated ectoderm containing nemato- 
cysts, &c. 
PLATE 43. 
Shows certain details of structure of the soft parts of Sporadopora dichotoma and of 
Astylus subviridis. 
Fig. 1. Section transverse to the longitudinal axis of a gastrozooid of Sporadopora 
