tive condition of the coral tracts of England and the rest of western Europe. No attention is paid to the existence of land masses.
Great Britain. Western Europe. Reefs. Deep-sea. Littoral. Reefs. Deep-sea. Littoral.
Trias.
Rhaetic.
A. planorbis.
A. angulatus.
A. Bucklandi.
Middle Lias.
Upper Lias.
Inferior Oolite.
Middle "
Coral rag.
Portland Oolite.
Neocomian.
Gault.
Cenomanian.
Lower Chalk.
Upper ".
Eocene.
Oligocene.
Miocene.
Crag-Pliocene.
Recent.
R after an asterisk denotes the paucity of reefs or of deep-sea conditions.
X. Corals and Coralliferous Deposits in consecutive Geological Periods.
The Trias.
There are no vestiges of coralliferous deposits in the British Trias. Formed as a marine deposit, the almost unfossiliferous Triassic sandstones were land- surfaces, whilst there were corresponding tracts reaching far away to the south-east, and great coral-reef areas to the east of the Vosges. The depth of the marine deposits of the Muschelkalk is very great ; and some of them contain compound Madreporaria and some simple forms. The reef origin of much of the dolomite may he inferred ; and the general affinities of the corals of the Muschelkalk and the St.-Cassian deposits indicate successive reefs upon nearly the same area, an elevation of the sediments of the first- named strata having occurred intermediately.
Rhoetic Series.
The subsidence of portions of the Triassic land surface in Britain accompanied the deposition of the Avicula-contorta beds and the White Lias. Some few stunted forms of littoral and deep-sea corals existed in the seas of the period in Great Britain. There were no reefs in our area ; nor are there any evidences of such structures in Europe, except in the Lombardian Alps and to the north of Savoy.
The Azzarolan deposits on the Lake of Como* contain abundance
- Stoppani, op. cit.
