THE HISTORY OF A DISCOVERS". 57 



ganism have been made by Professors King and Rowney : but 

 these appear to ine to be based upon the supposition that be- 

 cause some parts simulating organic structure are undoubtedly 

 mere mineral arrangement, therefore all parts are mineral. Dr. 

 Dawson has not proceeded upon the opposite supposition, that 

 because some parts are, in his opinion, undoubtedly organic, 

 therefore all parts simulating organic structure are organic ; 

 but he has carefully distinguished between the mineral and 

 organic arrangements. I am aware, from having supplied him 

 with a vast number of specimens prepared for the microscope 

 by the lapidary of the Canadian Survey, from a series of rocks 

 of Silurian and Huronian, as well as Laurentian age, and from 

 having followed the course of his investigation as it proceeded, 

 that nearly all the points of objection of Messrs. King and 

 Eowney passed in review before him prior to his coming to 

 the conclusions which he has published." 



Ascending Section of the Eozoic Rocks in tlie County of 

 Hastings, Ontario. By Mr. H. G. VENNOR. 



1. Eeddish and flesh-coloured granitic gneiss, the thick- Feet, 

 ness of which is unknown; estimated at not less than 2,000 



2. Grayish and flesh-coloured gneiss, sometimes horn- 

 blendic, passing towards the summit into a dark mica- 

 schist, and including portions of greenish- white diorite ; 

 mean of several pretty closely agreeing measurements, 10,400 



3. Crystalline limestone, sometimes magnesian, in- 

 cluding lenticular patches of quartz, and broken and 

 contorted layers of quartzo-felspathic rock, rarely above 

 a few inches in thickness. This limestone, which in- 

 cludes in Elzivir a one-foot bed of graphite, is some- 

 times very thin, but in other places attains a thickness 



of 750 feet ; estimated as averaging 400 



4. Hornblendic and dioritic rocks, massive or schis- 

 tose, occasionally associated near the base with dark 

 micaceous schists, and also with chloritic and epidotic 

 rocks, including beds of magnetite; average thickness 4,200 



5. Crystalline and somewhat granular magnesian 



