270 PROCEEDINGS OF THE AMERICAN ACADEMY 



ty. He had discovered, in the track of the tornado, a series 

 of points of greatest destruction, which succeeded each other 

 at constantly increasing distances. He endeavored to account 

 for the ascertained facts, by referring them to the collision of 

 a northwest and a southwest wind, of which he thought there 

 was satisfactory evidence. 



Dr. A. A. Gould stated some additional observations made 

 by him at the time of the occurrence of the tornado. 



Mr. Guyot, who had examined a part of the track of the 

 tornado with Mr. Blasius, testified to the accuracy of his ob- 

 servations, but did not coincide with him in his theoretical 

 views. 



Professor Peirce thought that some of the phenomena of 

 the tornado were incompatible both with Espy's and with 

 Redfield's theory of storms, and offered some objections to 

 the explanations of Mr. Blasius. 



Three hundred and fifty-first meeting. 



November 4, 1851. — Monthly Meeting. 



The President in the chair. 



Professor Agassiz gave an account of two families of fishes 

 not before observed in the United States, the Myxinoids and 

 the Erythrinoids, and described a new genus, Phyllobranchus. 



Professor Agassiz also communicated some new views in re- 

 gard to the geological position of the coal at Mansfield, Mas- 

 sachusetts, which led to an animated discussion, in which Mr. 

 Bouve, Dr. C. T. Jackson, and Professor Horsford took part. 

 He advanced the opinion, that the slate rocks at Nahant are 

 metamorphosed shales of the Mansfield coal formation; that 

 the sienite which overlies them is not the -cause of the meta- 

 morphic change, and is not an intruded rock, but is itself a 

 metamorphic sandstone of the coal period. 



Mr. Bouve remarked, that, if these views were correct, heat 

 must have been transmitted through the coal-bearing rocks 

 sufficient to melt down and render liquid or semi-liquid the 



