508 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 16, 



9. Calymene senaria. 



10. Pleurotomaria lenticularis ? 



1 1 . muralis f. 



12. Orthis, sp. f 



13. Lingula, sp. f 



14. Terebratula, sp. f 



15. Cytherina? f 



16. Syringopora. 



1 7. Pleurorhynchus ? 



18. Cephalic shield of a Trilobite 



allied to Illcenus arcturus f. 



19. Pustulated cephalic shield of an 



lUaenus t* 



20. Conularia, sp. 



21. Several specimens of the shield 



of Illaenus crassicauda. 



Note. — Those marked f are figured in Dr. Owen's Atlas of Illustrations. 



Many of these. Dr. Owen states, " are identically the same fossils 

 as occur in the lower part of ' Formation No. 3.' in Wisconsin and 

 Iowa, in the blue limestones of Indiana, Ohio, Kentucky, and also in 

 the Lower Silurian of Europe. The Coscinopora is precisely the 

 same as the coral which is particularly characteristic of the lower 

 beds of the Upper Magnesian Limestone of Wisconsin. The speci- 

 mens of Favosites basaltica cannot be distinguished from those 

 which abound in the Upper Magnesian Limestone of Wisconsin and 

 Iowa and the Lower Coralline beds of the Falls of the Ohio." 



It has been noticed that the limestones of this formation are di- 

 stinguished by two different tints of colour. From the following 

 analyses of the two varieties published by Dr. Owen, it would appear 

 that they differ also considerably in their mineralogical character. 



Analysis of the Compact Limestone 

 from Red River, containing Leptcena. 



Carbonate of Lime 53*7 



Carbonate of Magnesia 40*5 



Insoluble matter 0*8 



Alumina, Oxide of Iron, and 



Manganese 4*0 



Water and loss 1*0 



100-0 



Spotted and banded Limestone, con- 

 taining Coscinopora. 



Carbonate of Lime 78*1 



Carbonate of Magnesia 17*8 



Insoluble matter 1*0 



Alumina, Oxide of Iron, and 



Manganese 1*4 



Water and loss 1*7 



100-0 



It has been stated that none of the fossils from the Hudson's Bay 

 Basin hitherto submitted to Mr. Salter belong to the lower division 

 of the Silurian. It is proper to observe, however, that Mr. Salter 

 has expressed some doubt of the age of the limestone of Igloolik, 

 Melville Peninsula, and Amherst Island, amongst the organic re- 

 mains of which Professor Jameson and Mr. Stokes detected some 

 Trilobites, a Maclurite, and a Coral, which last fossil from the descrip- 

 tion given of it may have been a Receptaculites ; and it may be 

 added, that Marcou, apparently on the authority of Mr. Logan, 

 classes the limestones of Lakes Abbitibe and St. John as Lower 

 Silurian. The limestones of the Kakabeka Falls were identified by 

 himself as belonging to that division. The insufficiency of geological 

 explorations, and the want of published documents, render it impos- 

 sible as yet to define with any approach to accuracy the limits of the 

 two great divisions of the formation in this part of America, while it 

 may be safely asserted, however, that under one or other of its forms 

 the Silurian formation attains probably a wider development in the 

 Hudson's Bay Territories than in any other part of the world in 

 which its existence has been hitherto ascertained. Sir John Richard- 



