THE CANADIAN ENTOMOLOGIST. 351 



such characters should be used. Such habits are purely adaptive, and may 

 occur in widely-separated groups. Surely no one would think of 

 associating the Sabetiiineyb(5/^/'/rt nivipes with Ciilex and Culiseta simply 

 because it lays Its eggs in a raft. 



It would be unfair to criticize Mr. Thompson, whom Miss Mitchell 

 quotes, before he has himself presented his facts and conclusions. 

 Furthermore, it is impossible to discover from Miss Mitchell's wording 

 just how much is to be credited to Mr. Thompson and how much to his 

 spokesman. This much may be said, however : No safe conclusions as 

 to relationships can be drawn from the examination of a few detached 

 forms. Before formulating any theory of relationships some of the more 

 aberrant Culicine forms, such as Mansonta, ^deomyia and HcemagogiiSy 

 and at least one member of the Sabethine series, should be studied. 

 Perhaps the Sabethines, like the Corethrids, will be found to have four 

 instead of five malpighian tubes. I fancy that the' Sabethines will be 

 found to stand nearer the common ancestor than either the Culicines or 

 the Corethrids, but I await further data. In a consideration of the 

 relationships of the Culicidse with the other families of Nemocera, the 

 Psychodidas, which seems to have been omitted by Mr. Thompson, 

 should properly play an important part. That Anopheles is close to the 

 other Culicine forms, closer than most students are willing to admit, has 

 been the writer's belief for a long time. Miss Mitchell says " Culex may 

 be derived from Anopheles'' Never ! The reverse might be true, for 

 Anopheles is by far the more specialized form. 



The statement is made that the Corethrid larvae differ from those of 

 the Culicids by the " place of attachment of antennae " and '■ presence of 

 air floats." Neither of these characters holds good for the group, as Miss 

 Mitchell could have ascertained very easily, if material was unavailable, 

 by reference to published descriptions and figures. In Sayomyia and 

 Corethrclla the antennte are inserted close together at the front of the 

 head ; in Corethra and Eucorethra, however, the antennae are inserted at 

 the anterior angles of the head, just as in the Culicids. By " air floats " 

 we understand Miss Mitchell to mean the dilations of the tracheal tubes. 

 These reach their greatest development in the larv^ of Sayomyia, where 

 they re[)resent the respiratory system as four large detached air vesicles. 

 In Corethra these air vesicles are likewise present, but only form parts 

 of the main tracheal trunks. In the larvas of Etccorethra and Corethrella 

 these tracheal dilations are wholly absent ; they would be superfluous in 



