212 THE CANADIAN NATURALIST. [May 



ON A SUBDIVISION 

 OF THE ACADIAN CARBONIFEROUS LIMESTONES, 



WITH A DESCRIPTION OF A SECTION ACROSS THESE ROCKS AT WINDSOR, N.S. 



By C. Fred. Hartt, A.M. 



During several excursions made to Nova Scotia, previous to the 

 year 1864, I visited Windsor, Brookfield, Shubenacadie, and 

 Stewiacke, making extensive collections of the fossils of the 

 carboniferous limestone, so abundant at these localities. Taking 

 care to keep all the species obtained from any one bed or set of 

 beds separate from those from any other, I soon found that certain 

 oroups of fossils were limited in their occurrence to certain beds, 

 and that by means of these the whole series might be subdivided 

 somewhat after the manner of the sub-carboniferous limestones of 

 the west. In the summer of 1864, 1 spent some time in examining 

 the same ground, and in working out a section exposed on the river 

 Avon at Windsor. The collection made at that time I had an 

 opportunity, through the kindness of Prof. Agassiz, of examining 

 at the Museum of Comparative Zoology ; but before my studies had 

 been brought to completion, they were interrupted by my Brazilian 

 journey, and as I have in this city no facilities for resuming them, 

 I have sent, for determination, a considerable number of these fossils 

 to Dr. Dawson and Mr. Billings, so that ample material will be 

 afforded for the establishment of the faunal differences of the 

 subdivisions of the Acadian carboniferous limestones, which I shall 

 attempt to point out in this paper. 



On the right bank of the river Avon, at Windsor, a few rods 

 below the bridge, there begins a bluff, which, attaining in some 

 places a height of fifty or sixty feet, skirts the shore for the 

 distance of about half-a-mile above the bridge, when it gradually 

 descends into a tract of marsh, which occupies the shore for nearly 

 three-quarters of a mile further up, where there is a good exposure 

 of a heavy bed of limestone seen in a bluff, called the Otis King 

 rock. The bluff below the toll-house of the bridge is composed 

 of drift, a great part of the mass being derived from the under- 

 lying dark red, soft, friable, calcareous, marl-like sandstone. At 

 the toll-house the first rocks in situ appear buried deeply under 

 the drift deposit, thence southward, for about half the length of 

 the bluff above the bridge, the beds of carboniferous limestone, 



