200 THE CANADIAN ENTOMOLOGIST. 



Had Dr. Williston personally investigated the early stages of these 

 insects before writing his criticism, I feel certain that his view would differ 

 widely from that which he now holds. 



Admittedly, more than in any other order of insects, the early stages 



in the Diptera assume unusual importance in separating the order into the 



higher groups. Thus the primary divisions, Orthorhapha and Cyclorhapha, 



are founded entirely on larval characters and manner of pupation. The 



adults possess not one character whereby they may be separated from those 



of the opposite group, yet no one doubts the validity of the two divisions. 



In judging, therefore, of the value of groups in this order, it should be borne 



in mind that although the adult characters may sometimes appear but slight, 



still the group may be strongly marked as such by characters of the early 



stages. 



This important fact Dr. Williston ignores, and overlooks also the 



serious disadvantages under which Mr. Theobald was working, in being 



obliged to deal almost entirely with the adult forms, and in not being a 



trained dipterologist. Under these circumstances it must be admitted that 



Mr. Theobald acquitted himself very creditably. 



In criticising Mr. Coquillett's classification, especially that portion of 



it dealing with the subfamilies Psorophorinte and Culicinie, Dr. Williston 



may be pardoned for not being aware of the fact that these two subfamilies 



were separated chiefly by characters of the early stages. These, or any 



other characters of early stages of Culicidce, however, Mr. Coquillett is 



forbidden to refer to or even to study farther, in order that the field may be 



left clear for the nondipterologist, who claims it as " pre-eminently his 



own," and insists on its being reserved as such. Thus it happened that in 



Mr. Coquillett's classification only the weakest characters, those derived 



from the adults, were given. In passing be it noted that it is the 

 outstanding scales //«j the narrow wing scales which form the distinctive 

 character of the adult of the Psorophorinj>3, as well as the arrangement of 

 the outstanding scales, not the narrow scaling (//^//t', as Dr. Williston seems 

 to think was intended. Narrow or broad wing-scales alone would certainly 

 not distinguish a subfamily. Also, 1 agree with Dr. Williston that natural 

 genetic characters, such as palpal ones, should be used when present. 

 But if they are difficult of detection, and their finding involves the possible 

 destruction of the specimen, it seems as if some other more i)rominent, 

 even though artificial, character should be found if possible, to be used as 

 an accessory character for easy identification. 



In order that the standing of the two subfamilies, Psorophorinie and 

 Culicinae, may be more cleaily understood, their chief characters are here 

 appended : 



