166 THE SCOLYTID BEETLES. 



number of imdescribed species and a great amount of new biological 

 material. With this amount of material at hand and a special study 

 of this group of insects extending over a period of twenty years, the 

 writer feels justified in proposing a revised classification and in 

 defining the characters which it appears to him are of special taxo- 

 nomic importance. 



In presenting the preUminary classification of the Scolytoidea the 

 author does so with no idea of criticising the systems proposed by 

 other authors. The whole presentation is simply to stand as the 

 writer's interpretation of the characters and characteristics repre- 

 sented by the material before liim, and to serve, so far as it may, as 

 a step in the evolution of artificial systems of classification toward 

 the ideal or natural. Each comprehensive system of classification 

 proposed since that of Linnaeus has contributed something toward 

 the evolution of better systems. Some of them have been progres- 

 sive, others in part retrogressive, and a few have been revolutionary 

 in their character. But, as in most conflicts of opinion, general 

 progress results. Therefore those investigators of the present and 

 the future who, without prejudice as to any opinion or theory, can 

 sift out the true from the erroneous in that which has been published, 

 and add new truths from their own observations, will make the 

 most rapid progress toward the attainment of the ideal. 



The anatomical investigations conducted by the writer and out- 

 lined in Part I of this bulletin have revealed heretofore unrecorded 

 facts relating to structural characters, which, in connection with a 

 greatly increased knowledge of the physiological characteristics of 

 the stages of development and of the habits, host relations, and dis- 

 tribution of described and undescribed forms, seem to warrant a 

 somewhat different classification from those proposed by other 

 writers. 



It seems that a study of the facts as revealed by modifications in 

 morphological characters and physiological characteristics of exist- 

 ing forms, without any attempt to explain their origin or phylogeny, 

 will lead to a more correct interpretation of natural affinities than 

 any amount of speculation on hypothetical ancestral forms from 

 which present species may have evolved. Indeed, it would seem 

 that we have, in the progressive modification of the more funda- 

 mental and dominant characters and characteristics, a better taxo- 

 nomic basis on which to correlate the characters and construct a 

 so-called natural system than can be found in those characters which 

 are subject to special modification through similar use and influ- 

 ences of environment.'^ 



o In this connection see Part I of this bulletin, p. 25, second paragraph, and pp. 

 67-68. 



