226 THE VOYAGE OF H.M.8. CHALLENGER. 
C. Style of one of the dactylozooids, seen in section. 
B. Large canals of the coenosare, occurring in the pseudosepta or intervals 
between the dactylopores. 
S. Surface layer of the ectoderm. The main mass of tissue is composed 
of the finer ramifications of the ccenosarcal meshwork. 
Fig. 13. Small portion of the ccenosarcal meshwork of Sporadopora dichotoma, greatly 
magnified in order to show the histological structure ; as seen in osmic acid 
preparations. 
C. Channel of the canal. 
En, En. Endoderm layer. 
MM. Membranous layer. 
EE. Ectoderm. 
T, Nematocysts in process of development. 
Fig. 14. Two pigmented cells of the endoderm of the same, highly magnified. 
PLATE XII. 
Shows the structure of the ccenostea of several species of Stylasteride. 
Figs. 1-4. Stenohelia profunda, Off St Thomas, Danish West Indies. 450 fathoms. 
Bigs. 1, 2: Specimens drawn of the natural size to show the mode of branching. 
Fig. 8. A specimen enlarged to show the arrangement of the cyclo-systems. a@ Two cyclo- 
systems of the same, to show the mode in which the young terminal cyclo- 
systems bud out from the adult axial systems, and the arrangement of the 
ampullz around one of the latter. 
Fig. 4. Diagrammatic longitudinal section through two calicles such as shown in the 
foregoing figure. At the base of the tube of the young cyclo-system is seen 
the minute style. The ampulle are laid open. 
Figs. 5,6. Conopora tenuis. Off the Kermadec Islands. 650 fathoms. 
Fig. 5. A specimen drawn of the natural size. a@ The same enlarged. The stem is 
deformed, being enlarged, and hollowed out by a cavity occupied in the recent 
state by a parasitic Annelid. b Mouth of one of the cyclo-systems much 
enlarged. 
Fig. 6. Diagrammatic longitudinal section through one of the cyclo-systems to show its 
two chambers, the form of the gastropore and its connections with the 
dactylopores. 
Fig. 7. Cryptohelia pudica. Lat. 25° 45’ N., long. 20° 12° W. 1525 fathoms. 
