A MONOGRAPH 
OF THE 
BAI TISH FOSSIL CORALS. 
(SECOND SERIES.) 
INTRODUCTION. 
I.—Genrrat Anatomy or Recent Corats.’ 
MADREPORARIA, OR SCLERODERMIC ZOANTHARIA. 
Wuen a simple or solitary Coral is living in pure and well aerated sea-water its 
superficial soft tissues are noticed to form a disc, marked with a central depression and 
more or less covered by ¢entacules, as well as a covering to the general external surface.” 
The disc is superior, and the other soft tissues are inferior to it.$ 
The tentacles * surround the central mouth at varying distances; and the mouth is 
capable of being elevated above the level of the disc by the protrusion of a conical 
process.’ Certain ridges or radiating lines mark the sides of the mouth (the //ps), and 
extend outwards amongst the tentacules to the margin of the disc. 
The margin of the disc gives origin to those soft tissues which are visible on the 
outside of the coral. 
When any unusual stimulus is applied to the tentacules they contract, become smaller, 
and the conical mouth usually projects more than before.’ If the irritating influence 
persists, the mouth is retracted, the disc sinks, the tentacules disappear, and finally the hard 
parts of the calice come into view, covered simply by the flaccid and transparent soft 
parts. At the same time much water escapes through openings at the end of the 
tentacules, and the tissues covering the outside appear to lose their colour. 
1 The Introduction is illustrated by Plates I, II, III, IV, as well as by reference to some of the figures 
in those plates which refer more especially to species. 
2 Plate II, figs. 4, 9, 11, 12, 13, 16. 3 Plate II, figs. 12, 13, 16. 4 Plate II, figs. 4, 9, 11. 
5 Plate II, fig. 10. 6 Plate II, fig. 10. 
1 
