igo8] Habits of Insects as a Factor in Classification 83 



the ungulates, still another for the elephant, and a group covering 

 the primates. Comparing these it appears that the ungulate 

 and primate groups have really a closer relationship than either 

 of these with the rodent forms, although in existing classifications 

 the ungulate and rodent forms are embraced within the same 

 genus. It appears to me more in accord with the facts, especially 

 if we take into account this distribution and habit, to separate 

 the rodent forms, and this will necessitate the forming of a new 

 genus. 



Clasping organs show distinct types for a number of these 

 groups and quite varied forms in such apparently nearly related 

 species as those affecting Horses, Hogs, Cattle, etc. The Insect- 

 ivore type is extreme and introduces new features. 



We have traced a few of the many lines of adaptation that 

 have been followed by the groups of insects in their adjustment 

 to the many and varied conditions of life; adjustments so numer- 

 ous and so perfect that insects are today not only the most numer- 

 ous in species but fitted to a greater range of conditions than any 

 other class of animals. We certainly should take account of 

 these different conditions in our systems of classification if we 

 hope to have them represent the true relationships in nature. 

 We should use the lines of divergence in habit to point the way 

 to natural affinities. Distinct morphologic changes are almost 

 invariably associated with adaptations, if indeed, they are not 

 the direct response to these adaptations, and hence when habit, 

 distribution, function and structure are read together, we should, 

 if reading correctly most nearly approach the rational arrange- 

 ment of groups. 



I would not be understood as ignoring the fact that this prin- 

 ciple has been recognized in the past. Such names as Phytoph- 

 aga and Parasitica in Hymenoptera, Phytophaga, Mycetophaga, 

 Hydrophilus, Gyrinus, Cryptophagus, etc., in Coleoptera, or such 

 specific names as aquaticus, arborea, sub-terraneus, cavicola, etc., 

 testify to due appreciation of habits by many systematic workers. 

 But I wish to emphasize my belief that this principle may be used 

 to advantage not only in tracing larger phylogenetic lines but 

 in solving the perplexities of specific affinities among the minor 

 taxonomic groups. 



Students of animal behavior and psychology are beginning to 

 associate the differentiation of groups with psychic characters, 

 and such a claim as physiological species is not new even to ento- 



