PROCEEDINGS OF GEOLOGICAL SOCIETIES. 



231 



remarked that, in consequence of a fault bringing the Upper and Lower 

 Ludlow beds against one another, -without having altered their dip, many 

 fossils have been stated to occur in the Upper Ludlow which really belong 

 to the Lower. 



The following specimens were exhibited : — 



A specimen of Calais ISFewboldii, a new Octopod, from Mount Lebanon, 

 by J. de C. Sowerby, Esq. Palatal Teeth of CocJ/liodus, from the Carboni- 

 ferous limestone, by the Earl of Enniskillen. 



May 0>th. — 1. "On the Brick-pit at Lexden, near Colchester." By the 

 Rev. 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 Colue. The brick-pit shows 

 this table-land 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 MlepKas primigenius, 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. 



When 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 sedimentary origin, metamorphosed after 

 deposition, and sometimes after the production of cleavage and other phy- 

 sieal 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 paucity of informal ion concerning the Geology and Paleontology 

 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 Dr. Nugent, published 

 more than forty years 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 bears 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. I IV 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 he 

 t he chief features of the physical geography of the Miocene period, sub- 

 stituting a series of Archipelagos for the Atlantis of Professor I leer, and 

 stating that the Pacilic Ocean must have been at that period in immediate 

 connection with the Caribbean Sea. 



