380 Proceedings of Learned Societies. 



PROCEEDINGS OF LEARNED SOCIETIES. 



GEOLOGICAL SOCIETY.— April 27. 



Discovert of Fish in Upper Limestone of Permian Forma- 

 tion. — Mr. Kirkby communicated an account of the discovery of fish 

 remains in the upper limestone of the Permian formation. The 

 strata were exposed in some quarries ; the bed from which the fish 

 remains were chiefly obtained was that which is known as the 

 " Flexible Limestone." 



The author stated that at least nine-tenths of the specimens belong 

 to JPalceoniscus varians, the remainder belonging to two or three 

 species of the same genus, and to a species of Acrolepis. Detailed 

 descriptions of the different species of fish were given, as also were 

 short notices of the species of plants sometimes found associated with 

 them, one of which he believed to be Galamites aranaceus, a Triassic 

 species. The occurrence of Palceonisci with smooth scales was stated 

 to be antagonistic to Agassiz's conclusion that the Permian species 

 of that genus have striated, and the Coal-measure species smooth 

 scales. Mr. Kirkby remarked that the faunA of the period appeared 

 to be of an Estuarine character, and he expressed his opinion that 

 the fishes were imbedded suddenly, as a result of some general 

 catastrophe. 



The Fossil Corals of the West Indian Islands. BvMr. P. Martin 

 Duncan. — The results of the process of fossilization, as seen in the 

 West Indian fossil corals, is very remarkable, and has much obscured 

 their specific characters, rendei'ing their determination extremely 

 difficult. Hence it is desirable thoroughly to examine their different 

 varieties of mineralization, and to compare their present condition 

 with the different stages in the decay and fossilization of recent 

 corals as now seen in progress. Thus the author was enabled to 

 show the connection between the destruction of the minuter struc- 

 tures of the coral by decomposition, and certain forms of fossilization 

 in which those structures are imperfectly preserved ; and he likewise 

 stated that the filling up of the interspaces by granular carbonate of 

 lime and other substances, as well as the induration of certain species, 

 during a " pre-fossil " and " post-mortem " period, gave rise to 

 certain varieties of fossilization, and that the results of those opera- 

 tions were perpetuated in a fossil state. 



The forms of mineralization described by Dr. Duncan are — 

 Calcareous, Siliceous, Siliceous and Crystalline, Siliceous and 

 Destructive, Siliceous Casts, Calcareo-siliceous, Calcareo-siliceous 

 and Destructive, and Calcareo-siliceous Casis. 



In describing these forms especial reference was made to thoso 

 in which (lie structures were more or less destroyed during the 

 replacement by silica of the carbonate of lime of the coral. 



In explaining the nature and mode of formation of the largo 



ba of calices from Antigua, the author drew attention to the feet 

 that Hie silieification is more intense on the surfaco and in the 

 centre of the corallum than in the intermediate region ; and, when 



