78 REPORT—1868. 
the bottom of the reef and the top of the detritus will decrease very 
sensibly, and that any gradual elevation of the reef above the sea, pro- 
ducing its destruction, would be accompanied by a more rapid descent 
of débris. In after ages the upper and stony deposit would perchance be 
considered of different age from the marly and fine sediment below. Again, 
deep seas creeping over littoral areas and then over the land during the 
gradual subsidence of great areas would bring simple corals over littoral 
and terrestrial remains, the species all being really contemporaneous. On 
the other hand, a long-continued subsidence would equally tend to the increase 
of the reef and of the deep-water sediment. After the lowering of the area 
had been destructive to the reef, and no more detritus could fall, the usual 
ooze of the deep sea would gradually invade all. These suggestions will. 
perhaps render the occurrence of large coralliferous deposits in certain strata 
only, in large areas of formations, more comprehensible, and will tend to the 
belief that when coralliferous deposits occur at the base of a great series of 
uncoralliferous strata (and this is often the case) the idea of contemporaneity 
is not overcome by the evident succession of the deposits. 
The relation between such faune as the St.-Cassian and South Wales 
Lower Lias of the zone of Ammonites angulatus is evident; but the inter- 
mediate faunze of Azzarola and of the lowest zones of the Lias on the Con- 
tinent are less closely allied to the Welsh fauna. Again, the fauna of the 
Welsh Lower Lias is more closely allied to the Lower Oolitic Coral-fauna of 
England than are the Coral-faune of the zones of A. Bucklandi, A. raricos- 
tatus, and of the Middle and Upper Lias. 
How interesting is the affinity between the Coral-fauna of Gosau and the 
Miocene Coral-fauna of the Caribbean area! yet the British Chalk hardly 
represents any part of the Gosau fauna, and our Eocene fauna has no 
resemblance to it. These considerations tend to prove how vast and com- 
plicated the gradual migrations must have been, even of animals which 
could only live under very definite and limited conditions, how really con- 
temporaneous were the species entombed in vast consecutive deposits, 
how complicated the relations of the fauna have ever been, and how clearly 
the absence of corals from strata does not prove their absence in adjoining 
and equivalent areas. The notion that successive new creations of corals 
followed repeated destructions of faunse is not supported by a single fact; on 
the contrary, all the evidence disproves it. The amount of individual varia- 
tion, of gradual structural changes, and of decided variation amongst the 
Madreporaria is not without significance ; and the examination of large series 
of forms from all parts of the world, and from consecutive formations, im- 
presses the belief in the continuous evolution of new forms by variation from 
the old during the whole of the Coral ages. 
Fossil Corals from the Crag. 
The following authors have written upon this subject :—Searles Wood, Ann. 
& Mag. Nat. Hist. 1844, vol. xiii. p.12. Lonsdale, Searles Wood’s Catalogue, 
Ann. & Mag. Nat. Hist. 1844. Milne-Edwards and Jules Haime, “ Mém. sur 
les Astraides,” Comptes Rendus de l’Acad. des Sciences, vol. xxvii. p. 496 
(1868); “‘ Monog. des Turbinolides,” Ann. des Sciences Naturelles, 3rd ser. 
vol. ix. (1848); Hist. Nat. des Corall. 1857, Paris. R. C. Taylor, Mag. 
Nat. Hist. 1830, vol. iii. p. 272. G. de Fromentel, ‘ Introd. 4 l’Etude des 
Polyp. Foss.’ 1858. 
The Sclerodermic Zoantharia, or true Madreporaria, are rarely found in 
any of the Crags. Bryozoa abound, and thus gave the term “ Coralline ” to 
