168 



He also was disposed to regard the antler as a dermal bone, 

 rather than a portion of the endo-skeleton ; 1st, because it i^ de- 

 veloped in the integuments by a special centre of ossification, and 

 only becomes attached to the frontal bone after ossification has 

 somewhat advanced ; 2d, because the permanent antlers of the 

 Giraffe do not become united with the cranium except by suture 

 until late in life, and are developed over the parietal as well as 

 the frontal bones, without being divided on the line of the sutures 

 of these two bones, which they would be were they merely epi- 

 physes of them. 



November 2, 1859. 

 The President in the Chair. 



Prof. William B. Rogers exhibited a fossil cast in sandstone of 

 part of the trunk of a large Sigillaria, from the South Joggins in 

 Nova Scotia, where, as first shown by Logan and Dawson, these 

 and other stems belonging to the carboniferous age occur at nu- 

 merous levels in the strata, and are to be seen standing in the 

 erect position in which they grew. 



In considering the process by which these stems were origi- 

 nally enveloped by the mass of sediment now inclosing them in 

 the shape of sandstone and shale, an inquiry of much interest is 

 sucrcrested as to the rate of accumulation of the deposit in which 

 they are huried. Many of these erect trunks are of very consid- 

 erable height, and one is mentioned by Sir Charles Lyell as 

 traceable vertically across the strata for a distance of twenty-five 

 feet. In all such cases the decay of the tree could have made no 

 great progress before the trunk became buried to the whole ob- 

 served depth, otherwise it would have become too weak to main- 

 tain an erect position, and must have fallen over. We infer, 

 therefore, that the mass of sediment even to the height of twenty- 

 five feet, in the case above cited, must have been accumulated 

 around the stem in a period extending at farthest only to the ear- 

 lier stages of change in the organic structure. Moreover this 

 conclusion is strongly confirmed by the fact, that the peculiar 



