Dr. Nicholson on Intrusive Igneous Rocks of the Lake-district. 391 



1868 were particularly described by the author from his personal 

 observations. 



9. " Notes on certain of the Intrusive Igneous Rocks of the Lake- 

 district." By Dr. H. A. Nicholson, E.G.S. 



The rocks referred to in this paper were the syenite of the Vale 

 of St. John, the syenitic porphyry between Ennerdale and Butter- 

 mere, and the felstone porphyry of Carrock roll. The author de- 

 scribed the characters and position of these rocks with regard to 

 the Skiddaw Slates on the one hand, and the green slates and por- 

 phyries on the other, and indicated that the latter series of rocks 

 are un conformably deposited upon the purely sedimentary Skiddaw 

 Slates. The Skiddaw Slates were said to be metamorphosed where 

 they come into contact with the intrusive masses, and the latter were 

 regarded by the author as most probably "the roots of the ancient 

 vents from which were derived the alternating ashes and traps 

 which together compose almost the whole of the green-slate series." 



10. " On the Fossil Myriopods of the Coal-formation of Nova 

 Scotia and England." By Samuel H. Scudder, Esq. 



In this paper the author discussed and described the species of 

 Chilognathous Myriopods which have been detected in the Coal- 

 measures. Of these he recognized 6, viz. Xylobius sigillarice (Daws.), 

 X. similis, sp. n., X. fractus, sp. n., X. Daivsonii, sp. n., X. Wood- 

 ivardii (= sigillarice, Woodw.), and a species upon which he founded 

 a new genus, Arcluulus ccylobioides. He regarded these forms as 

 constituting a peculiar family, for which he proposed the name of 

 Archiulidce. 



11. "On the Geology of the Country surrounding the Gulf of 

 Cambay." By Alexander Rogers, Esq., E.G.S., Bombay Civil Service. 



The author described the surface of the country as consisting 

 chiefly of deep alluvial soils, derived from the denudation of the 

 primary and metamorphic rocks surrounding the district, the former 

 making their appearance in groups of isolated peaks, projecting, as 

 it were, from a sea of alluvium. The author considered that this 

 alluvium could not have been produced by the action of the existing 

 rivers, and suggested that the Indus may formerly have flowed into 

 the sea by the Gulf of Cambay, the land at the same time being 

 much depressed below its present level. He indicated the evidence 

 in favour of this view furnished by various facts in the geology of 

 the district, and referred especially to the mode of occurrence of 

 laterite. 



12. " On a new Acrodont Saurian from the Lower Chalk." By 

 James Wood Mason, Esq., E.G.S., of Queen's College, Oxford. 



The author described this reptile, for which he proposed the name 

 of Acrodontosaurus Gardneri, as differing from Mosasaurus in the 

 apparently persistent distinctness of the prsemaxilhe and their small 

 development in the middle line, in the more anterior position of the 

 nasal aperture, which is directed upwards and forwards, in the total 

 obliteration of the maxillo-prsemaxillary suture, and in the absence, 

 from the cylindrical teeth of opposite denticulated ridges. The 



