GEOLOGY. 263 



been done in the accurate identification of the constituent min- 

 erals of the rock mass. Tlie jDresent paper was a statement of 

 the result of the examination of a substance that, from the indefi- 

 nite character of its composition, partakes of the nature of a rock 

 rather than that of a min(3ral. It consists of a specimen of obsid- 

 ian from Java, originally in the cabinet of Bernard Woodward, 

 Esq., but the label does not give the exact locality. It appears 

 to differ much from that, also from Java, now in the British Mu- 

 seum. The specific gravity of the specimen now produced is 

 2.35 ; in thin sections it is joerfectly transparent. The lecturer gave 

 a complete analysis of its composition, wdiich he said may be 

 easily cut into thin sections, and by the aid of a low power, say 

 200 diameters, at least three distinct minerals (beautifully crys- 

 tallized) may be distinguished, diagrams of which were produced 

 ■with the specimen. These, with the optical properties, were ad- 

 mirably described, some doubt being expressed as to the nature of 

 th^second mineral; but the third was undoubtedly composed of 

 magnetic iron. 



Mr. Thomson then read a paper "On Teeth and Dermal 

 Structure associated with Ctenacanthus as well as on new forms 

 of Pieroplax and other carboniferous Labryinthodonts and of 

 Megalichtys.'''' Sir Philip Egerton, who is a great authority ou 

 fossil fishes, took the chair, for the purpose of being able to com- 

 ment on the subjects mentioned in the paper, which were of a 

 purely technical character. Sir Philip Egerton mentioned sev- 

 eral instances where genera had been founded on dift'erent charac- 

 ters of the same fish. The main object of the communication 

 was to show that several so-called genera of fossil teeth were in 

 reality small spines. Mr. Thomson had proved, from actual dem- 

 onstration, that three or four genera of fossil fish could be 

 resolved into the same genus. 



A short communication was made by Mr. W. CaiTuthers "On 

 Reptilian Eggs Irom Secondar}^ Strata." Some of the eggs were 

 Chelonian, or turtle, in their character. Many of them had all the 

 appearance of fruit. They had a peculiarly glossy appearance, 

 and were very thin. Mr. Carruthers went into some detail on the 

 origin of small shalvcneides found in coal shale, and explained 

 how they had been formed by gas or air. 



M. de Tchipatchef gave a short viva voce account of the Palae- 

 ontology of Asia Minor. To this he has devoted twenty years of 

 his life. Mr. Godwin Austen said M. de Tchipatchef was well 

 known as the most enterprising Asian traveller, and all geolo- 

 gists had derived great profit from his labors. 



"Occurrence of Stylonarus in the Cornstone of Hereford." 

 This was a new species of crustacean. Mr. Woodward also read 

 a few notes" On the discovery of a large Myriapod, of the genus 

 Euplioheria, in the coal measures of Kilmaurs." This fossil is a 

 centipede nearly two inches long. Their occurrence in the Brit- 

 ish coal measures is very rare, although Dr Dawson had found 

 them in the strata of South Loggins, Nova Scotia. The legs, etc., 

 of the fossil could be plainl\' seen with a low optical jDOwer. Mr. 

 Godwin Austen said nothing was more interesting than the nu- 



