62 



Through an oversight, proper credit was not given in Bulletin 

 No. 5 to Prof. A. G. Wetherby, who discovered all the forms 

 therein described from the Trenton Group of Mercer county, Ky., 

 and Knox county, Tenn. ; also, those from the Kaskaskia Group, 

 of Pulaski county, Ky., as well as those from the Keokuk Group 

 of Tennessee, in all some fifteen species, including one new family 

 and three new genera. And the opportunity is here taken not 

 only to make this correction, but to express to Prof. Wetherby 

 our sincere thanks for the valuable assistance he has rendered 

 in securing interesting specimens, as well as valuable information. 



