8 THE CANADIAN ENTOMOLOGIST. 



2S7-8, that the Diptera are by far the most specialized insects, and that 

 they should therefore be considered the highest in rank. If any one still 

 doubts that they are the most specialized, he may be referred to the late 

 edition of Lowne's Anatomy etc., of the Blow Fly, part I., Oct., 1890. 

 The wonderful development of the muscid pupa from the imaginal discs, 

 all the larval organs undergoing disintegration, is not paralleled in any 

 other order of insects. I contend that specialization, as deduced from 

 the ontogeny of the insect, is the best and only reliable criterion of rank. 

 Let those who believe otherwise point out a better one. To talk of an 

 intellectual development in insects is absurd. I do not admit that the 

 actions of the social hymenoptera are in any way actuated by reason or 

 intellect. It is, rather, inherited habit. 



As to the ubiquitousness of the House-fly, this is rather a point in its 

 favour. It has, entirely on its own resources, become emphatically cosmo- 

 politan, and even man " in all his glory " is unable to reduce its numbers, 

 or in any way to cope with it. On the other hand, the Honey-bee has for 

 ages been cultivated, cared for and protected by mankind. Yet I would 

 not by any means suggest the House-fly as the climax of insect 

 development. 



Man is the highest animal, because of his immense cerebral specializ- 

 ation. There is no such contrast in cerebral development between the 

 lowest and highest insects as there is even between the anthropoid apes 

 and man. Consequently I believe that the same factor should not be 

 used as a criterion of rank in insects. At the same time, man is farthest 

 removed from the ancestral mammalian form in his general structural 

 development, as deduced from his ontogeny, and this can and should be 

 used as the basis of argument, not only in insects, but in all other groups 

 of animals. 



This line of reasoning puts the Diptera at the head of the insect body, 

 inasmuch as their larval stages show greater specialization or development 

 than the larvse of any other order of insects, while their perfect form 

 points them out still more emphatically as the farthest removed from the 

 ancestral thysanuriform type. 



If there is an objection on the part of some to the term " highest ", 

 let the expression " most specialized " be substituted therefor. I cannot 

 help believing that the use of the latter would be preferable. 



