224 THE CANADIAN NATURALIST. [May 



life over the regions they occupy. Might not some material be 

 gathered from this new and rich field bearing on that vexed 

 question of descent with modification ? 

 New York, May 28th, 18G7. 



Note by Dr. Dawson. — Much credit is due to Mr. Hartt for 

 the careful manner in which he has worked up the succession of 

 fossils in the limestones of the Avon estuary. I have endeavoured, 

 in the new edition of Acadian Geology, to apply his results to 

 other parts of Nova Scotia. In regard to the resemblance of the 

 Windsor fauna to the permo-carboniferous of the west, it is to be 

 observed — (1) That no such distinction as sub-carboniferous and 

 carboniferous can hold in Nova Scotia. The Windsor fauna is 

 simply the marine fauna of the carboniferous, and some of the 

 beds may be coeval with the coal measures, as I suggested many 

 years ago (Acad. Geol. 1st. Ed.). (2) The lithological character 

 of these beds is like that of the permian, and similar sea bottoms 

 of different periods often present resemblances of fauna. (3) 

 That the fauna in question actually lived in the lower carboniferous 

 period, is proved by the sections in Cumberland, Pictou and Cape 

 Breton, which show the limestones with these shells lying below 

 the productive coal measures. (4) It is to be observed that the 

 supposed premo-carboniferous fades applies to the upper members 

 of the Windsor limestones more especially. I have fully illustrated 

 these points in the new edition of Acadian Geology. 



