PLATE 17, 18. 
CORAL. LIMESTONE, QUARTZ, AND CHERT, 
FIG. 1. 
ERI^MOLITHUS (Madrepores, cespitosa) Madrepora: 
fasciculatac stirpibus cauUformibus teretibus subra- 
mosis striatis flexuosls bine coalescentibus, stellis 
terminalibus turbiaato-concavis reticulatis. S. p. 
Fossil coral. The original a Madrepora, compound, fas- 
ciculate. Stirps caullform or stalk-like, round, somewhat 
branched, * striated slightly in a longitudinal direction, flex*- 
uose, and, in some parts, coalescent. The stars are termi- 
nal, turbinato-concave, and reticulated. 
Not uncommon about liakewell, Winster, Castleton, and 
other places where the limestone strata oceur. Frequently 
chert with the matrix limestone. 
The best specimens of this, as Well as of the other fossil 
corals, are found in the loose stone walls, with which the 
lands in many parts of Derbyshire are fenced. In such, or 
similar situations, where the limestone has been broken into 
small pieees, and exposed for a length of time to the action 
of the weather, the surface is generally found to be more 
or less decomposed and Washed away ; while the chert or 
quartz which constitutes the petrifactions, if the stone con- 
