8 INTRODUCTION. 



Of such common species as the household centipede ( Scut ig era forceps) 

 and the "silver fish" or " slicker" {Lepisma spp.) careful studies yet 

 remain to be made, and it is hoped that one of the incidental benefits 

 which will result from the publication of this bulletin will be this indi- 

 cation of topics of desired investigation to students. The illustrations 

 have all been made by Miss Sullivan, with the exception of those of 

 the cheese skipper and ham beetles and the house centipede, which 

 have been prepared by Mr. Otto Heidemann. All drawings have been 

 made under the supervision of the author of the section in which they 

 appear. 



L. O. H. 



