A CKNO WLED G ME NTS. 



ix 



Prof. C. P. Gillette loaned for reproduction figure No. 150. 

 Mr. Frank Sempers, of Philadelphia, kindly gave figure No. 

 49- 



Mr. H. G. Hubbard, of Washington, obligingly loaned figure 

 No. 359. 



Of the machinery illustrated, an electrotype of No. 476 was 

 supplied by Mr. McGowen, of 478 by Mr. William Stahl, and 

 of 479 by W. & B. Douglas. 



The following are originals, and were especially prepared for 

 this work: Nos. 2, 3, 8, 9, 18, 19, 20, 21, 24, 25, 54, 57, 63, 

 66, 67, 69. 113, 126, 135, 153, 154, 155, 184, 185, 215, 248, 249, 

 250, 251, 252, 257, 266, 267, 272, 285, 304, 305, 306, 322, 323, 

 344, 345> 346, 348, 379, 41 5, 43^, 453, 477- Of these original 

 figures, some are photographs, others are from drawings by the 

 author, some are redrawn, and a few are duplications of published 

 figures where no plates were known to be in existence. 



To all who have in any way aided in the preparation of this 

 work, and especially to Mr. L. O. Howard, of Washington, who 

 kindly read my chapter on Hymenoptera, and Prof Lawrence 

 Bruner, who kindly read my chapter on Orthoptera, I tender 

 my sincere thanks. 



