264 PROCEEDINGS OF THE AMERICAN ACADEMY 



and parallel with each other, are so perfect as to produce the 

 effect of a regularly fluted column wrought with a chisel. In 

 some parts of these grooves, there are carbonized remains of 

 the original plant. It is otherwise a perfectly silicified fossil 

 of a grayish-white color. Mr. Lyell, who has visited the spot 

 (South Joggins) from which the specimen came, has satisfac- 

 torily determined that the strata of sandstone, in which the 

 Sigillaria and other coal fossils of Nova Scotia are found, 

 form altogether a mass of 2,500 feet in thickness. As these 

 fossils are dispersed through every part of this immense mass, 

 at the lowest depth as v/ell as near its surface, Sir Charles 

 Lyell concludes that many forests which grew here must 

 have been successively submerged, and changed to the con- 

 dition in which we now find them. The fossil trees are in 

 an erect position, and perpendicular to the planes of stratifica- 

 tion of the sandstone ; but as this rock is now inclined at an 

 angle of twenty-four degrees, we have proof of its subsidence 

 or change of position.* 



Three hundred and forty-sixth meeting, 

 April 15, 1851. — Semi-monthly Meeting. 



The President in the chair. 



Professor Peirce presented a paper on Saturn's rings, by 

 Mr. George P. Bond, in which the latter gentleman has care- 

 fully investigated the structure of those rings, and arrived at 

 the result, that they are fluid, and variable in number. Professor 

 Peirce also stated, as some of the results of his own researches 

 uj)on the same subject, that no ring can exist around a planet 

 which has not satellites ; that a ring surrounding such a planet 

 would fall into it ; and that a fluid ring surrounding Saturn 

 might at the maximum become subdivided into twenty rings. 



Professor Agassiz communicated some new views upon the 

 special homologies of Echinoderms ; and pointed out, at con- 

 siderable length, homologies in the structure of several speci- 



* See Lyell on American coal plants, in his Travels in .Xorth Jmerica, Vol. II. 



p. I5y. 



