10 CLASSIFICATION OF THE ALEYRODID^. 
worthy of mention that in minimus Quaintance (PI. I, fig. 8) the 
cubitus is represented by a faint line or fold and in conspurcatus 
(PI. I, fig. 6) it is retained, this latter species possibly being a con- 
necting form. 
In the genus Aleurochiton (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 grouped in the subfamily Aleyrodina?. Here 
the costa and subcosta are united to form one vein. Radius x 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 x 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 
sa} 7 s, speaking of fragarice 16 "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 v This is borne 
out also by the pupa, which has no large compound pores. The care- 
ful work of Miss Patch 14 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 ngures 44 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 (PL 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 pcrsece 
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 Aleurodicus by the reduction of the 
media and radius v This view is also borne out by the structure of 
the pupa, which has the compound pores of Aleurodicus, and of the 
