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REPORT ON CORALS—EXPLANATION OF PLATES. 
A. Former ; A’, recent calicular cavity. 
C, C. Tabule. 
B. Portion of wall of tube cut parallel to its surface, in which a line of 
suture between the fibres of opposite systems composing it is to be 
observed. 
D. Vertical canal. 
P. Point of growing coral showing lines of successive growth. 
The numbers 1, 1’; 2, 2”, &e., indicate the order in which the succes- 
sive chambers were formed. 
Fig. 6. Portion of the hard tissue forming the wall of a tube cavity of Heliopora cerulea, 
from the same preparation as fig. 5, more highly magnified. 
Ce Ass: 
B. Shaded band caused by the fact that part of the calcareous tissue is 
stained of a more intense blue than the remainder. A similar band is seen 
on the opposite side of the axis. 
. 7. a, a Two of the cells of the endoderm of Heliopora cerulea; one of these with 
the contents undergoing fission. 
b’ Nematocyst of the same. 6 A form of nematocyst commonly to be 
observed in which the thread is partly protruded and curved in a 
loop, whilst one side of the cell is bulged in. 
Fie. 8. Ovum of Heliopora caerulea as attached to the mesentery. 
Fig. 9. Diagram to show the growth of Heliopora by a process of successive buddings 
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Ojo) 
and developments of tabule. 
A. The original calicle of the stock: A’, A”, &c., successively formed 
chambers in continuation of this calicle; 1, 2, 3, successive lateral 
buds. 
B. Formation of a new ealicle. A short tube buds out, but the tubes on 
either side of it grow more quickly. Only the outer part of their 
walls continues to be developed; hence a wide circular cavity 
is formed with the original short tube at its bottom. 
Fig. 10. Drawing by Dr J. J. Wild, Artist to the Challenger Expedition, of the rapidly 
crowing tip of a frond of Heliopora cerulea. 
The young growing tubes of the coonenchym are polygonal in area. 
A A. Calicles in various stages of formation. 
11. By the same. A calicle nearly fully developed, as seen when looked directly 
into. The calicle is surrounded by irregular dentations, of which there are 
more than twelve. A circlet of coenenchymal tubes is seen to join the cavity 
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of the calicle below. 
