TAB. XVII. 
CORALS FROM THE CORAL RAG. 
IsASTREA EXPLANATA (p. 94). 
Fig. 1. Side view of a specimen, in which the epitheca has been partly removed in 
order to show the mode of arrangement of the cost ; natural size. 
la. Calicular surface of the same; natural size. 
1 4. Calice, magnified. 
1c. Horizontal section, magnified. 
1d. Specimen, in which the calicular fossula has been filled up by a calcareous 
deposit that assumes the appearance of a tuberculose columella. 
IsasTREA GREENHOUGHI (p. 96). 
Fig. 2. Portion of the calicular surface somewhat worn ; natural size. 
ae 
'THAMNASTREA CONCINNA (p. 100). 
Fig. 3. Side view of a large specimen ; natural size. 
3a. A portion of the common basal plate, showing the wrinkled epitheca; natural 
size. 
3 6. Calices in a good state of preservation, magnified. 
3c. Calices much weather-worn, magnified. 
