MR. H. N. MOSELEY ON THE STRUCTURE OF THE STYLA.STER1D2E. 
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ticallj, towards the surface of the planula. In these tracts the 
nematocysts are developed. 
B. A layer of the same elements lying next to the outer surface of the 
endoderm. 
Fig. 8. A portion of the same planula, viewed from the surface, to show the manner 
in which the surface is marked out into polygonal areas, by the special 
arrangement within the substance of the ectoderm of the nematocysts and 
tracts in which they are developed. 
N, N. Nematocysts, seen in optical section. 
A, A. Elements amongst which they are developed. 
Fig. 9. Section, vertical to the surface, of a nearly-mature planula of Errina labiata. 
E. Ectoderm, composed of alternate transparent and more opaque tracts, 
disposed vertically to the surface. 
A. The more opaque tracts, containing numerous nuclei and young 
thread cells. 
B. Basement membrane. 
En. Endoderm, composed of fatty bodies and granules, and containing — 
N, N. Developing nematocysts ; 
O. Large oil globules. 
Fig 10. Portion of the surface layer of the ectoderm of Errina labiata, viewed from 
the outer surface. 
S, S. Polygonal nucleated cells composing the layer. These in places 
overlap. 
N, N. Nematocysts seen in situ within these transparent superficial cells. 
Fig. 11. Section, vertical to the surface, of the ectoderm of a gastrozooid of Errina 
labiata. 
E. Superficial layer, composed of inflated transparent nucleated cells. 
E . Inferior layer of the ectoderm containing numerous nuclei. 
Fig. 12. Section, transverse to the axis, of a cyclo-system of Allopora profunda, taken 
at some little distance below the level of the mouths of the pores of tne 
zooids, showing the sac only of the retracted gastrozooid in section, but 
both sacs and zooids of the dactylozooids. The whole is represented 
as decalcified, with the exception of the styles of the dactylozooids, which 
are introduced to show the position which they occupy in the recent state 
of the coral (cf. Plate 39). 
R, It. Radially disposed offsets of the coenosarc. 
G Z. Cavity of the sac of the gastrozooid. 
X, X. Interradial spaces between these. 
D Z. Dactylozooid, showing in section its three composing layers, 
ectoderm, endoderm, and intermediate muscular and membranous 
layer. 
