169 



thought might be PedicillaricB. He had never been able 

 to detect in them a tubular structure. They always occur 

 at the corners of the plates. 



Mr. Desor said, that in studying the development of the 

 Starfishes he had noticed these bodies and believed them 

 to be suckers. They always occurred at the corners of the 

 plates. The F edicillarm in Echini are scattered about 

 without any regard to symmetry. 



Prof. Rogers alluded to the fact, that Mr. Salter had 

 recently demonstrated in London the fallacy of Hugh 

 Miller's argument for the deterioration of species, based on 

 the supposed existence of fishes in some of the older rocks 

 of a higher organization than those of a more recent period. 

 He remarked, that the only evidence remaining of the 

 existence of Vertebrata in the Silurian system was a single 

 occurrence of foot-prints in the Sandstone of the St. Law- 

 rence Valley. With regard to the nodules like Coprolites 

 occurring in the Barlow Limestone, he suggested that the 

 same source which could supply Phosphate of Lime to 

 Coprohtes might supply it in the form of Concretions to the 

 Geological formation itself; so that the occurrence of such 

 nodules merely was not positive proof of the existence of 

 fishes at that period. 



Dr. Jackson said, that nodules of simple Phosphate of 

 Lime are not unfrequently met with. Coprolites would 

 contain bones, scales, &c., which would leave no doubt of 

 their character. 



Prof. Rogers inquired if Dr. Jackson, in his examinations 

 of the Hillsboro' coal, had found any traces as of the mo- 

 tion of the mass in a soft, semifluid condition. 



Dr. Jackson replied that he had not. 



Prof. Rogers said that he thought he had himself ob- 

 served it. Cannel coal breaks with a conchoidal fracture 

 indifferently in all directions, with strict parallelism of lami- 

 nation. The Hillsboro' coal on the other hand, shows in 

 places appearances of having been solidified in the condi- 



