I'KKUMIXARY NOTE. 



The preparation of the following memoir was begun by Mr. Garman 

 during my term of service as Director of the Kentucky Geological Sur- 

 vey. Circumstances have made it necessary to delay its publication to 

 the present date. 



In the act of L874, providing for the continuance of the Geological Sur- 

 vey, the Legislature of Kentucky permits "that the scientific results of 

 the Survey may be published in any scientific journal by permission of 

 the Director." Although this memoir will form a part of the second 

 volume of .Memoirs of the Kentucky Survey, it seems to me highly 

 desirable that it should secure the wider circulation that will he given 

 to it by this publication in the memoirs of the Museum of Comparative 

 Zoology. The Kentucky Survey is fortunate in being able, by this 

 arrangement. t<> acknowledge the large debt it owe- to this Museum for 

 most effective aid in f\<'r\ step of its scientific work. 



X. S. SHALER, 



Formerly Director of '/<-' Kentucky Geological Sw 



Cambridge, Mass., June, 1883. 



