10 CLASSIFICATION OF THE ALEYRODIDiE. 



worthy of mention that in miniinus Quaintance (PL I, fig. 8) the 

 cubitus is represented by a faint line or fold and in conspurcatus 

 (PI. I, fig. 0) it is retained, this latter species possibly being a con- 

 necting form. 



In the genus Alem'ochiton (PI. I, fig. 10) this state of affairs does 

 not hold, but an opposite line of descent is indicated and the forms 

 showing this may be grouj^ed in the subfamily Aleyrodinaj. Here 

 the costa and subcosta are united to form one vein. Radius ^ and the 

 radial sector are present as in Aleurodicus. The media, however, is 

 absent or only faintly indicated in freshly emerged specimens. The 

 cubitus, on the contrary, is well retained and forms a distinct vein. 

 It may be noticed here that the pupa of Aleurochiton has not the 

 large compound pores of Aleurodicus. 



In examining a wing of the genus Aleyrodes (PI. I, fig. 11) we 

 see that the costa and subcosta are again united, the radial sector is 

 retained, but the radius ^ has disappeared. In some material a faint 

 rudiment of this vein is noticeable. The media, as in Aleurochiton. 

 has entirely disappeared and is made out plainly only in the fresh 

 wing. In some species, however, the rudiment of this vein is notice- 

 able and has been observed as early as the time of Signoret, for he 

 says, speaking of jragaHm ^® " Dans cette espece, entre la nervure 

 mediane et la nervure oblique de la base, j'en ai observe le commence- 

 ment d'une seconde." The cubitus is here retained and forms the 

 second vein of the wing. It is evident, then, that Aleyrodes is an off- 

 shoot from Aleurochiton by the reduction of radius i. This is borne 

 out also by the pupa, which has no large compound pores. The care- 

 ful work of Miss Patch ^* on tracheation in this genus corresponds 

 exactly with our observations. She figures and describes the vena- 

 tion in Aleyrodes sp. and shows clearly that the second vein of the 

 wing is the cubitus. Her words are, " The second vein of the wing 

 of Aleurodes is cubitus, as will be seen by comparing figures 41 and 

 45, where the second vein is shown to follow the courses of the cubital 

 trachea." In this family Miss Patch, however, treated only the genus 

 Aleyrodes. 



The venation in the genus Paraleyrodes (PI. I, fig. 9) appears at 

 first glance like that'of Aleyrodes^ but more careful study shows it 

 to be very different. The costa and subcosta are here united and the 

 radial sector is retained. The second vein of the wing, however, is 

 not the cubitus, but the remnant of the media, and can be found as a 

 branch of the main vein. Moreover, in some specimens of persece 

 the cubitus can be seen faintly indicated in its usual position. This 

 venation shows, then, that Paraleyrodes is not closely related to 

 Aleyrodes, but is a branch from Aleurodic^is by the reduction of the 

 media and radius ,. This view is also borne out bv the structure of 

 the pupa, which has the compound pores of Aleurodicus, and of the 



