PHOCEEDINGS OF GEOLOGICAL SOCIETIES. 
231 
remarked that, in consequence of a fault brlnj^nnpr tlie Upper and Lower 
Ludlow beds against one another, without having altered their dip, many 
fossils have been stated to occur in the L^pper Ludlow which really belong 
to the Lower. 
The following specimens were exhibited : — 
A specimen of Calais Xeioholdii, a new Octopod, from ]Mount Lebanon, 
by J. de C. Sowerby, Esq. Palatal Teeth of CocJdiodus, from the Carboni- 
ferous limestone, b}'^ the Earl of Enniskiilen. 
^lay 6th. — 1. " On the Brick-pit at Lexden, near Colcliester." By tlie 
Eev. Osmond Fisher, M.A., F.G.S. ; with a note on the Coleoptera, by T. 
V. Wollaston, Esq., F.L.S. 
Lexden is a village about a mile west of Colchester, and is situated on a 
plateau on the south side of the Valley of the Colne. The brick-pit shows 
this table-laud to consist of thick beds of gravel and sand, resting upon 
the London Clay, and containing at its southern extremity a talus of old 
gravel. This stratified gravel is overlaid by brick-earth and soil, and is 
believed by the author to be that which elsewhere underlies the Boulder- 
clay ; and he states that between it and the brick-earth there is, in one 
locality, a layer of peat containing bones of Elephas primlgenius, and the 
remains of many insects ; the latter are considered by Mr. Wollaston to 
differ from British recent species, and to indicate a warmer climate than 
now obtains in the district. 
2. " On the original nature and subsequent alteration of Mica Schist." 
By H. C. Sorby, Esq., F.K.S., F.G.S. 
TVhen ripples are formed whilst material is being deposited, there is a 
structure generated which the author has, in former papers, termed 
" ripple-drift," and which he now described. This structure he stated 
might frequently be seen in polished sections of clay-slates, and also, in a 
form modified through metamorphism, in many mica-schists. From a 
consideration of the facts revealed by an examination of those rocks, he 
concluded that mica-schist is of sedimentars' origin, metamorphosed after 
deposition, and sometimes after the production of cleavage and other phy- 
sical changes ; and that the bands of different minerals represent the planes 
of original deposition. 
3. " On the Fossil Corals of the West Indies."— Part I. By P. Martin 
Duncan, Esq., F.G.S. 
The paucit}^ of information concerning the Geology and Palaeontology 
of the West Indies, and the deficiency of carefully described species of 
recent corals, were stated to have involved this subject in great obscurity. 
Dr. Duncan, however, remarked that the paper by I)r. Nugent, published 
more than forty j^ears ago, showed the existence in Antigua of three con- 
secutive Coral-formations, called by him (in ascending order) — 1, the in- 
clined strata ; 2, the chert ; 3, the 'marl. 
After describing in detail the seventy species and varieties of Fossil 
Corals from the West Indian Islands which he had been able to deter- 
mine, Dr. Duncan exhibited in the form of tables the relation which this 
fossil fauna br nrs to the existing fauna of the Caribbean Sea, and to that 
of the Pacific, South Sea, and Indian Ocean, showing that it is more nearly 
related to the latter than to the former. He also showed that it bears a 
closer relation to the European Miocene coral-fauna than to the recent 
West Indian ; and he therefore considered it to be most probably of Mio- 
cene age. The author concluded by describing what he believed to be 
the chief features of the physical geograph}^ of the Miocene period, sub- 
stituting a series of Archipelagos for the Atlantis of Professor Heer, and 
stating that the Pacific Ocean must have been at that period in immediate 
connection with the Caribbean Sea. 
