TRANSACTIONS OF THE SECTIONS. 65 
very closely and elaborately sculptured, and encircled by two or three coloured bands, 
was dredged by Sir Edward Belcher off the Cape of Good Hope, from a bank of 
dead shells, corallines, &c., at the depth of 132 fathoms. 
_ All the species of Voluta hitherto known in a recent state are of comparatively solid 
structure, characterized by a copious deposit of enamel on the body whorl on reaching 
maturity, and none exhibit any detail of sculpture beyond that of longitudinal ribs. 
The species under consideration is not identical with any of the tertiary species, but 
of the same type more minutely latticed, similarly coronated, so to speak, and with a 
similar channeled excavation round the spire. 
It is proposed to name it Voluta abyssicola, and it will be described and figured in 
the Mollusca of the Voyage of the Samarang. 

Prof. W. B. Rogers exhibited the State Survey of Virginia, geologically coloured, 
and gave a general sketch of the structure of the country, with especial reference to the 
Faults in the Alleghanies. The State of Virginia comprises an area of 66,000 square 
miles, containing four distinct physical and geological districts :—1st, the Tertiary plain 
on the Atlantic; 2ndly, the rising ground consisting of gneiss, mica-slate and other 
primitive rocks, which lies between the coast plain and the Alleghanies, with- the 
oolitic coal-field of Richmond occupying a depression on its surface; 3rdly, the Alle- 
ghany mountains; and 4thly, tlie great western coal-field. The Alleghanies consist of 
numerous parallel ridges of palzozoic rocks, ranging north-east and south-west, sepa- 
rated from the primitive region by the “ Blue ridge,” a tract of igneous and highly 
altered rocks, which may be regarded as the igneous axis of the State. ‘The anti- 
elinal ridges of the Alleghanies all lean to the westward; and this want of symmetry 
increases towards the “ Blue ridge,” until the strata forming the western flanks of 
each ridge are completely inverted, and dip under those on the eastern side; these 
great foldings and inversions of the strata are frequently attended by enormous faults, 
the western side of a ridge being absolutely engulphed and the eastern over-riding 
it; in these cases the Lower Silurian rocks sometimes rest on the inverted carboni- 
_ ferous limestone, and even on the conglomerates of the coal-measures: the displace- 
ment of the strata must amount in many instances to 10,000 feet; but if a fault is 
os traced to a great distance either way, it is found to diminish gradually and terminate 
_ ina mere flexure of the strata; the length of the faults is sometimes more than 100 
miles. Prof. Rogers then mentioned the occurrence of workable anthracite below the 
_ earboniferous limestone of the Alleghanies. In conclusion, he stated that during a 
_ recent tour in the Alps he had observed a general conformity in the structure of those 
mountains with the law of flexures exhibited in the Alleghanies; that is to say, the 
greatest dip of every anticlinal and synclinal was on the side furthest removed from 
__ the axis of disturbance: so that the general direction of the ridges and the curvature 
of the strata would now afford indications of the direction of the dynamic agency 
by which those flexures were produced. 



2 _ On the Age of the Saurians named Thecodontosaurus and Paleosaurus. 
¢ By Wiuxram Sanpers, F.G.S. 
3 
The remains of these animals were discovered in the year 1835 by Dr. Riley and 
Mr. Stutchbury, who state that the dolomitic conglomerate in which they were im- 
_ bedded forms the base of the new red sandstone, adopting the views announced by 
Dr. Buckland and Mr. Conybeare, in their Memoir of the Bristol Coal District. 
_ This memoir was published in 1822, accompanied by a map and sections, which re- 
| present distinctly the conglomerate rocks as constituting the lower division of the new 
_ red sandstone. The age thus assigned to these fossils was adopted by all geologists ; 
_ itis so described in the best elementary works, and enters into the general statement 
| made by Professor Owen in his Report on Fossil Reptiles. The Ordnance maps and 
_ sections present no alteration in this respect; they likewise represent the conglo- 
_ merate as completely subjacent to the later new red. 
Nevertheless the elaborate essay of Sir Henry De la Beche ‘ On the Formation of 
Rocks in South Wales and South-western England,’ in the first volume of Reports of 
_ the Geological Survey, contains such a description of the new red sandstone beds as 
to lead the reader to concur with him in believing, that such conglomerates and 
_ limestones “ may be of different dates,” and that “the cause of their production con- 
1849, 5 
a 
