COKAL RAG. 
339 
MIDDLE OOLITE. 
Coral Rag.—One of the limestones of the Middle Oolite 
has been called the “ Coral Rag,” because it consists, in 
part, of continuous beds of petrified corals, most of them 
retaining the position in which they grew at the bottom of 
the sea. In their forms they more frequently resemble the 
reef-building polyparia of the Pacific than do the corals of 
any other member of the Oolite. They belong chiefly to 
the genera Thecosmilia (Fig. 322), Protoseris^ and Thamna- 
Fig. 322. 
Ihecosmilia annularis^ Milne Edw. 
and J. Haime. Coral Rag, Steeple 
Ashton. 
Fig. 323. 
Thamnastrcea. Coral Rag. 
Steeple Ashton. 
strma^ and sometimes form masses of coral fifteen feet thick. 
In the annexed figure of a Thamnastrcea (Fig. 323), from 
this formation, it will be seen that the cup-shaped cavities 
Fig. 324 . deepest on the right-hand side, and 
that they grow more and more shallow, 
until those on the left side are nearly 
filled up. The last-mentioned stars are 
supposed to represent a perfected con¬ 
dition, and the ^25 
others an im- 
Coral Rag, mature State. 
Steeple Ashton. coralline 
strata extend through the calcare¬ 
ous hills of the north-west of Berk¬ 
shire, and north of Wilts, and again 
recur in Yorkshire, near Scarbor¬ 
ough. The Ostrea gregarea (Fig. 
324) is very characteristic of the 
formation in England and on the 
Continent. 
One of the limestones of the Jura, 
referred to the age of the English NeHnoea Ooodhaiin.mnoZ Coral 
coral rag, has been called “Neri- Rag, Weymouth, inat.size. 
naean limestone” (Calcaire a Nerinees) by M. Thirria; N'eri- 
