THE CANADIAN KNTOMOLOGiaT. 31 



The variation in the epistoma of Z>. vakns, as illustrated in fig. lo, 

 will prove interesting to those familiar with the genus. It will be remem- 

 bered that Dr. Dietz based his classification of this genus largely upon the 

 characters of the epistoma, which he considered of specific value. I have 

 never been able myself to find any such variations as Dr. Hopkins has 

 figured. Thus again is emphasized the value of a long series of specimens 

 in a study of this nature. 



The last half of the work deals with the description and classification 

 of the species. Including the new forms described, twenty-four species 

 are now contained in the genus. The method of treatment is systematic 

 and thorough. The species are usually discussed under the following 

 sub-heads: i\dult, Variations, Distinctive Characters, Pupa, Larva, 

 Galleries, Distribution, Host Trees, Identified Specimens, Bibliography 

 and Synonymy. A drawing of the adult and a chart showing the distribu- 

 tion are given in each case, and usually excellent figures of the galleries 

 are included. 



The bewildering tangle heretofore presented by the literature dealing 

 with several of the species has been cleared up completely, and the 

 " Revisional Notes '' under certain of the species are invaluable. 



Ifseful tables arc given of the Secondary Sexual Characters, I'upul 

 Characters, Larval Characters, Gallery Characters, Distribution, Relation 

 of Species to Host Trees, and of the Host Trees themselves. A very 

 complete Bibliography of the genus is given at the close. 



More detailed descriptions of the new species described might 

 perhaps have been desirable, in view of future descriptive work, and the 

 key to the adult, while excellent, seems to present a few weak points ; 

 however, a perfect key to the genus Dendroctonus is hardly to be expected 

 in this life. 



The work throughout is systematic and complete, one of the best 

 productions of its kind yet given us by American Entomologists. 



All students of the Scolytidse will look forward with the greatest 

 pleasure to the completion of Dr. Hopkins's " Monograph of the Scolytid 

 Beetles.'' — [. M. Svvaine. 



Our Insect Friends and Enemies: By John B. Smith. Lippincott 

 Co., Philadelphia. ($1.50.) 



This book of 314 pages is the most interesting and comprehensive, 

 popularand yet scientific account of insects as the friends or enemies of 

 man, that we have yet seen, 



