1869.] DUNCAN—CORAL FAUNAS OF WESTERN EUROPE. 65
Godwin-Austen and Sharp concerning the relations of the English
Upper Green Sand and Lower White Chalk,—that, in fact, the first
deposits were covered by the last during a period of subsidence, and
that oceanic conditions prevailed over the littoral. Since the corals
of the Gosau district have been compared with those of Les Bains de
Rennes, the Montagne des Cornes, Martigny, and Figuieres, it has
become evident that large tracts of the French, Spanish, and Austrian
areas were occupied by coral reefs, which were formed and destroyed,
after producing enormous sediments, whilst the oceanic conditions of
the British, Belgian, and North German areas prevailed. There were
also deep-sea formations going on far away to the east whilst the
reefs of Gosau were flourishing. Yet the oceanic conditions outlasted
those of the reefs, and the sediments of the deep sea evidently
covered up those of the reef-areas as the great subsidence of the
period progressed. There were then two coral faunas living at once
on the Western European area. The reef-species were very numerous,
and were closely allied not only to the Neocomian forms, but
also to those of the Oolites. The alliance is greater with the Neocomian
fauna than with the Oolitic; but there is a remarkable similarity
of "facies" between the three groups of forms, which reminds
the naturalist of the peculiarities of the existing corals of the Pacific.
This arises from there being many genera which were represented
in the Lower Cretaceous reefs, and which exist in those of the
Pacific.
The fauna of the Upper and Lower White Chalk, on the other hand, is essentially represented by that of the existing deep-sea coral fauna of the North Sea and the Atlantic, on the west coast of Ireland, down to the Straits of Gibraltar. The Caryophyllioe of the Chalk are closely allied to the existing species, and the branching Synhelia is represented by Lophohelia. The homotaxis of the Cretaceous deposits and those now forming is very extraordinary.
The uppermost deposits of the White Chalk in Denmark and Holland contain a few traces of shallow-water and reef corals; and the end of the Cretaceous coral-period resembled that of the Oolitic.
Nummulitic Period.
The fossil corals of the London Clay, Bracklesham, and Barton beds, indicate varying bathymetrical conditions: some of the species were littoral, and others were wanderers from a reef-area. The corresponding deposits on the other side of the Channel contain many of the British species, and were formed under the same external conditions. The reefs of the period covered vast areas. The typical reefs were in Styria, about Oberburg; others were in the Vicentin, the Tyrol, Switzerland, the Maritime Alps, Corbieres, Nice, the Pyrenees, and Biarritz. The reefs were continued into the Crimea, Egypt, Syria, and Arabia; and the Hala Mountains, in Sindh, contain as great an aggregation of reef-making genera as modern reefs. The Oberburg fauna was highly developed, and contained all the varied styles of maeandriforin, branching, and massive corals
VOL. XXVI.—PART I. F
