356 PROCEEDINGS OF THE AMERICAN ACADEMY 



J, Lothrop Motley, Esq., in Class III., Section 3. 

 Hon. Charles Francis Adams, in Class III., Section 4. 

 Hon. George S. Boutwell, in Class III., Section 4. 



Four hundred and tliirty-sixtli meeting. 



February 10th, 1857. — Monthly Meeting. 



The Academy met at the house of the Hon. Nathan Ap- 

 pleton. The President in the chair. 



The Corresponding Secretary read letters from J. Lothrop 

 Motley and Charles Francis Adams, accepting Fellowship, 

 and also one from J. Stuart Mill, in acknowledgment of his 

 election as Foreign Honorary Member. 



Professor Agassiz exhibited a cast of a fossil shell, recently 

 obtained at Santa F^ de Bogota, which he had just received 

 from Paris. The specimen was remarkably perfect, and be- 

 longed to the genus Chryoceras, which has been referred to 

 the family of Ammonites. It is an interesting question, bear- 

 ing upon the law of correspondence of geological succession 

 and order of position in living races. To what order of the 

 Cephalopoda do the Ammonites belong ? 



Professor Agassiz proceeded to point out the characters of 

 the two great divisions of the class, the Acetabulifera and the 

 Tentaculifera, showing that there are characters in certain 

 species of each which resemble those of species in the other 

 class. He did not regard the position of the Syphea in the 

 chambered shells, whether dorsal or central, as of much con- 

 sequence as a distinctive feature, but rather its relative posi- 

 tion. The fact of its being central or dorsal depended merely 

 upon the animals being coiled one way or the other. Among 

 the Gasteropoda, examples of reversed shells are well known. 



In conclusion, therefore. Professor Agassiz was inclined to 

 refer the Ammonites to the class of Acetabulifera, separating 

 them from the Nautiloids among the Tentaculifera, with which 

 they have been hitherto associated. All Nautili are smooth, 

 whereas all Ammonites are ornamented on the surface. The 



