PREFACE 



Ix presenting this, the sixth volume of its Proceedings to the scientific 

 public, the Davenport Academy of Natural Sciences indulges the hope that 

 it may be found to merit a reception no less favorable than that accorded 

 to its predecessors. 



It is the expectation of the Academy to publish at shorter mtervals in the 

 future than in the past, meanwhile issuing important papers as heretofore 

 in brocliure form, as soon as possible after their reception. 



The recent endowment of the Publication Fund of the Academy by Mrs. 

 Mary L. D. Putnam, Chairman of the Publication Committee, in the sum of 

 nine thousand five hundred dollars, as a memorial to her husband, Charles E- 

 Putnam, and her son, Joseph Duncan Putnam, provides for it assured finan- 

 cial support to the extent of the interest of the sum mentioned. 



Early m the history of the organization (1876) the publication of Pro- 

 ceedings was begun under great difficulties by that indomitable young 

 scientist, J. D. Putnam, and during the short remainder of his life he bent 

 his energies toward placing it on an enduring basis. To this end he was 

 ably assisted by his father, who not only lent the moral support of his ap- 

 proval, but was ever ready to respond to appeals for material aid, and it is 

 eminently fitting that the father's name should be associated with that of 

 the son in this memorial endowment. 



The first signature line of the present volume bears date, December 14 

 i8g2, the twenty-fifth anniversary of the Academy's founding. Since then 

 the unsparing hand of death has removed many of those most closely con- 

 nected with its origin and growth. 



The demise, shortly after his removal to Minneapolis, of Professor W. H 

 Pratt, deprived this Academy of a life-long and enthusiastic worker for all 

 pertaining to its interests and those of science in general. A life member 

 and one of the original group to whom it owes its existence, on his foresight 

 and energy the Academy had learned very largely to depend, and his loss 

 is most deeply felt. 



Among other prominent members who have passed away since this vol- 

 ume was begun, are Rev. S. S. Hunting of Des Moines, a former President 

 and life member; William H. Holmes of this city, an earnest supporter; 

 and Israel Hall, a friend and life member; while the scientific world at 

 large has suffered irreparable loss in the death of Professors John Tyndall 

 and C. V. Riley, both honorary members, and Charles Wachsmuth, a cor- 

 responding member of the Academy. 



With a steady growth in its Museum and Library, the latter now num- 

 bering over thirty thousand volumes, the Academy yet feels sorely both the 



