62. REPORT—1868. 
extensive beds of limestone and sandstone, characterized by Ostrea biauriculata 
(and which are entirely wanting in England and the north of France), known as 
the Grés du Mans, are found interposed between the base of the Lower Chalk and 
the highest beds of Chalk-marl. 
Proceeding towards the Pyrenean basin more important modifications occur. 
The Grés du Mans is much more largely developed, and comprises a great abun- 
dance of Rudistes. Above this layer are found the marly beds of the Lower Chalk; 
and above these again, the Angoumien, Mornasien, and Provencien strata, equivalent 
together to a thickness of 2000 feet. 
n the basin of the Loire another horizon is found, which, in its turn, supports a 
solid limestone abounding in other species of Rwudistes; and with this, the Craie 
moyenne of the south-west and south of France terminates. 
The author then proceeds to describe the Upper Chalk as composed of four dis- 
tinct layers, each characterized by a distinct fauna, and neither of which are met 
with in England or in the basin of the Seine. In the west of Provence these beds 
are largely developed ; and M. Coquand has given diagrams and lists of the charac- 
teristic fossils, which seem to differ essentially from those found in similar beds 
elsewhere. 
M. Coquand then gives a description of the Upper Chalk of Provence, dividing 
it into Conzacien (ferruginous limestone), Santonien (of which the upper portion is 
fluviatile), and Campanien and Dordonien, both consisting of freshwater limestone, 
with eighteen distinct beds of lignite, and attaining a thickness of from 1500 to 
1800 feet. The Campanien and the upper part of the Santonien furnish large 
quantities of coal; and, indeed, Marseilles and the surrounding district are entirely 
dependent upon these beds for their supply of this mineral. 
The cretaceous beds of Algeria are next described, and their correspondence, as 
regards their fauna and position, with the Provengal strata before described is 
shown; and after observing that by a comparison of Algeria with Provence, Pro- 
vence with Charente, Charente with Sarthe, Sarthe with Paris, and Paris with 
England, we shall be able to recognize the various links of the Cretaceous system, 
M. Coquand suggests that the divisions hitherto recognized by English geologists 
are altogether inadequate to indicate the true character of the chalk, and that if a 
general classification of these strata were now to be established, the preference 
ought to be given to Provence, on account of the facility of finding those divisions 
larger and more numerous, and, in short, presenting more classical types. 
On the Formation of certain Columnar Structures. By J. Curry. 
On the Genus Clisiophyllum. 
By Dr. P. Martin Duncan, F.R.S., F. and Sec. Geol. Soe. 
Great numbers of specimens of several species of this genus abound in the 
Lower Carboniferous limestone of the Scottish coal-field at Beith, Ayrshire, Les- 
mahagow, Lanarkshire, Bathgate, Linlithgowshire. 
Mr. J. Thomson, of Glasgow, whose photographs of sections of Carboniferous 
Corals were exhibited at the last Meeting of the Association, has forwarded me 
about 200 fine specimens, carefully cut in sections, and in excellent order. 
A careful examination of these has enabled me to arrive at the following con- 
clusions :—Dana, the great American zoophytologist, originated the genus, and 
M‘Coy, following Dana, gave new species of it to science, and had sections of his 
types chogenglnd in Sedgwick’s celebrated work on the Paleozoic fossils. 
Milne-Edwards and Jules Haimes retained Dana’s name Clisiophyliwm in their 
description of the genus in the Introd. Pal. Soc., in their Des. des Pol. des Terrains 
Palzoz., and in their Hist. Nat. des Corall. But they have added a most im- 
portant structural peculiarity to the genus. Doubtless they had better specimens 
than Dana and M‘Coy; for nothing can be more evident than the existence in the 
axis of the corals of the genus of a great lamella, ending at the bottom of the 
calice ina prominent ridge. The ridge was noticed by the previous authors, but not 
the lamella. Yet this lamella determines the peculiar construction of the central 
parts of the coral. M‘Coy, in the description of one of his species, says that a 
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