TAB. XVIII. 
CORALS FROM THE CORAL RAG. 
THAMNASTREA ARACHNOIDES (p. 97). 
Fig. 1. 
as 
nas 
We: 
ld. 
ites 
Side view of an adult specimen; natural size. 
A young specimen ; natural size. 
Calicular surface of a young specimen, slightly magnified. 
Side view of a young specimen, the growth of which has been intermittent. 
Calices magnified. 
Variety having the calices disposed in almost parallel series, and placed at a 
greater distance than usual ; natural size. 
Some of the calices of this last variety, magnified. 
. A specimen much weather-worn, in which the terminal portion of the calices 
has disappeared and the walls have become prominent; natural size. 
. Some well-preserved costa, magnified. 
Some weather-worn costa, magnified. 
(See 1g, at the left-hand bottom corner.) A specimen, the calicular surface 
of which is shghtly worn down ; natural size. 
. A specimen much modified by the process of fossilization ; natural size. 
