24 Introduction 



the point at which it is in approximate accord with a sequence otherwise 

 established. 



I cannot refrain from insertmg a few words on environmental 

 adaptation. I have already alluded to the three-fold division of the 

 Coleoptera indicated by the digestive system. This is in a measm-e 

 confirmed by the modifications of the palpi. In papers read before the 

 New York Entomological Society some years ago, but still unpublished, 

 I tried to show that while the chief environmental factor for plants might 

 be moisture, for beetles it was certainly food; and profound structural 

 modifications were correlated therewith. This is naturally nowhere 

 more marked than in the mouth parts and especially in the palpi. 

 Assuming, as I feel compelled to do, the habit of feeding (possibly in 

 very moist, swampy localities) on decajdng matter, vegetable and 

 animal indifferently, as the primitive habit of beetles, it is found to be 

 associated with the simplest form of digestive apparatus and with 

 mouth parts of varied form, but extreme in no direction. 



It is noteworthy also that among such forms the blattoid larva 

 is also most frequently found. The habit of feeding on animal matter 

 is associated with a more complex digestive system and with the equiva- 

 lent of six palpi. The habit of feeding on living vegetable tissvie is 

 associated with an equally complex, but different digestive system, 

 and a gradual atrophy of palpi, practically complete in the highly deriva- 

 tive Rhynchophora. 



It may still be true that the extinction of the most primitive of 

 polj^Dhagous families leaves the Adephaga possessed now of the greatest 

 aggregate of primitive characters (as indicated on p. 21), but if such 

 be the case, it does not necessarily imply an origin for them antecedent 

 to that of all Polyphaga. While, therefore, I place Adephaga first, my 

 doing so is more because Leconte did so than because I believe they 

 are more prunitive than every family of Polyphaga; and while I have 

 arranged the families of Polyphaga in accordance with the phylogenetic 

 table on p. 21, including with them Rhysodidse and Cupesidae, it is 

 not my intention to conceal the heterogeneous character of the assem- 

 blage. It seems better, however, to retain existing errors if such there 

 be, rather than to risk introducing new ones on no better basis than 

 disputable phylogeny. 



Explanation of Chart 



Having thus estabUshed with a fair degree of certainty the sequence 

 in which the series should be placed, I will now endeavor to exhibit 

 the position, in the series, in which the families and some of thek most 



