A MOIS^OGRAPH 



OF THE 



BEITISH FOSSIL COKALS. 



(SECOND SERIES.) 



INTRODUCTION. 



I. — General Anatomy of Recent Corals.^ 

 Madreporaria, or Sclerodermic Zoantharia. 



When 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 tentacides, 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 /2}?s), 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, 11, 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, IC. ^ pjate II, figs. 12, 13, 16. * Plate II, figs. 4, 9, 11, 

 5 Plate II, fig. 10. 6 Plate II, fig. 10. 



1 



