TRANSACTIONS OF THE SECTIONS, 63 
large septum exists across the central area, but in another place, and in his draw- 
ings there is nothing of the kind. 4 
Those paleontologists who study from M‘Coy are therefore at a very great dis- 
advantage. The correctness of the views of Milne-Edwards and Jules Haimes is 
beyond a doubt, and Clistophyllum of Ed. and H. is thus readily separable from 
the closely allied genera Aulophyllum and Cyclophyllum. The genus is interesting, 
because the apparent prolongations of the septa over the central boss to the colu- 
mella are indications of the pali which abound in many Mesozoic genera, and also 
because it is closely allied, from its minute structure, with the well-known com- 
pound forms of Lonsdaleia and Lithostrotion. This alliance was asserted by Dana. 
The specimens prove that, although they may be arbitrarily divided into three 
species, still the gradation of structure between the types of these species is per- 
fectly shown in some of the numerous examples. Moreover, the variation in some 
of the structures, which are generally considered sufficiently stable to be safe 
guides in species-making, is immense. In fact no better proof can be given that a 
species is the sum of a greater or less amount of variation, instead of a fixed and 
efinite matter, than that afforded by these Scottish corals. 
The specific differentiation must be decided, not by the shape, or size, or septal 
number of the corals, but by the size of the central area, the obliquity, straightness, 
and quantity of the endotheca generally, and the number and direction of the 
septa which cover the central area. 
On the Denudations of Norfolk. By the Rev. O. Fisuer. 
The author first called attention to the denudations upon the land surface, 
stating that a certain amount of the fine material was being carried into the rivers, 
and by them deposited at the heads of the broads or inthe sea. This denudation by 
pluvial action was undoubtedly greater where the land was under the plough 
than it would be otherwise. Upon the coast the sea was reducing the solid surface 
to a uniform level. Where the land was high it cut away the bottoms of the 
cliffs, which then foundered down, and the fallen matter was in its turn carried off; 
and where it was low the general contour of the coast was being continued by sand 
dunes or “ Marram Hills ;” so that where the end of a valley was submerged, its 
bottom was being raised seaward, and reduced to a uniform level and continuous 
coast-line. But when the waves had played their part, the action of the sea was 
not ended. As the sea cut further into the land, the ground laid under water became 
subject to the action of tides, so as to be kept, on the whole, at a uniform depth 
for a given distance from land. If the waste of the shore was prevented by arti- 
ficial means, the sea was found to deepen rapidly, and the inclination of the bottom 
from the shore to be increased. This marine action, if considered, did not appear 
possible to give rise to any very great inequality of surface, but, on the other hand, 
it must tend to reduce those already existing. 
All great inequalities of the sea-bottom must either have been caused by the 
land having become submerged more rapidly than the sea had time to move its 
coast-line, or else by elevations and depressions taking place beneath the ocean, 
or, in a few instances, by powerful currents confined by local circumstances to a 
narrow course. Since the tides deepen the sea below the level to which the waves 
act upon the coast, it must follow that the harder rocks must be lowered more slowly 
than softer ones, and shoals be formed. It was to such a denudation as that just: 
described that the form of the surface of this county might be supposed to be due 
at the period preceding the deposition of the Crag. It might be safely supposed 
that the sea-bottom at the period of the Crag consisted of a shoal bottom of chalk, 
nearly level on the eastern side of our area, while the same stratum rose as dry 
land to a considerable elevation towards its central and western portions. But 
there was no distinct indication of the position and ancient coast-line of the Crag 
sea, though, no doubt, it extended further inland than Norwich, Horstead, and 
Coltishall ; indeed the author saw no reason to doubt that the remnants of ferru- 
inous shelly gravel adhering to the surface of the chalk on the beach at Lower 
herringham belong to it. The appearance of the chalk at Bungay and of the 
Upper Norwich Crag at Aldeby, near Beccles, would place the junction of the two 
deposits somewhere between Beccles and Bungay. 
