8 RECORDS 



when this case is contrasted with that of the introduced P. 

 cynthia. As reported last spring, selection in the latter species 

 is similarly of the less variable individuals, but is "secular" as 

 well, that is, the perfectly metamorphosing pupae form a class 

 by themselves, with a type which differs from that of the whole 

 group. It was pointed out that the real basis of selection was 

 probably a correlative one, a physiological "fitness" depending 

 upon the proper coordination or correlation of the various parts 

 of the organism. 



Henry E. Crampton, 



Secretary. 



SECTION OF GEOLOGY AND MINERALOGY. 



January 20, 1902. 



Section met at 8 : i 5 P. M., Dr. A. A. Julien presiding. The 

 minutes of the last meeting of Section were read and approved. 



The following program was then offered : 



R, P. Whitfield, Observations on and Emended Descrip- 

 tion OF Heteroceras simplicostatum White. 



R. P. Whitfield, Description of a New Teredo-like Shell 

 FROM THE Laramie Group. 



James Douglas, Notes on the Rio Tinto Copper District. 



Summary of Papers. 



In the first paper Professor Whitfield emended and elaborated 

 the description of the ammonite, Heteroceras siniplicostatuni 

 which he gave originally in the Newton and'Jenney Report on 

 the Black Hills ; ^ the new observations being based upon ma- 

 terial collected in July, 1901, for the American Museum of 

 Natural History by Dr. E. O. Hovey. The present material 

 shows conclusively that the three genera, Hamites, Ancyloceras 

 and Heteroceras, have no independent existence, because single 

 individuals possess the distinguishing characters of all three 

 genera combined. The fact that these genera were not inde- 



1 Report on the Geology and Resources of the Black Hills of Dakota. With 

 atlas. By Henry Newton, E.M., and Walter P. Jenney, E. M., Washington, 

 1880. Palaeontology by R. P. Whitfield. 



