18 CLASSIFICATION OF THE ALEYRODIDiE. 



lost, the cubitus is retained, and no pupal compound wax pores are 

 present. This divides the family at once into two distinct sub- 

 families to which the names Aleurodicinse and Aleyrodina? may be 

 applied. Outside of these two subfamilies we have the form Udamo- 

 selis pigmentarla, which is much more generalized than any other. 

 It retains both media and cubitus and we place it, at present, alone 

 in the Udamoselinse. We have included in the Aleyrodinse three 

 genera, Aleurochiton^ Aleyrodes, and Neomashellia. The first is the 

 most primitive, and fi'om it Aleyrodes has arisen by the reduction 

 of radius 1. NeommkelUa^ however, seems to have separated earlier 

 than Aleyrodes, for it retains very hairy psyllid-like claspers and 

 the wing venation is more reduced. The genus Aleyrodes at present 

 includes many diversified forms and a careful study of these will 

 no doubt necessitate the breaking up of the genus. 



In the subfamily Aleurodicinse the most primitive fonn seems to 

 be Dialeiirodictis cocherellii. This species, while it has developed 

 the wing venation of Aleurodicus, still retains head characters which 

 ally it to Udamoselis. The pupa, too, has no compound wax pores 

 as in the genus Aleurodicus. With this species as type, Cockerell 

 erected Dialeurodicus and placed it as a subgenus of Aleurodicus. 

 It is evident, however, that this does not represent its true position, 

 but that it is considerably older than Aleurodicus. We therefore 

 make it the type of a genus rather than a subgenus. The species 

 described as Aleurodicus lahillei, as discussed under wax pores 

 (p. 14), shows characters intermediate between Dialeurodicus and 

 Aleurodicus. These characters are so marked and evidently inter- 

 mediate that we make it the type of a new genus, Leonardius, allied 

 to Dialeurodicus in wing form, vertex, and vasiform orifice, and 

 showing a development toward Aleurodicus in wax-secreting struc- 

 tures. The genus Aleurodicus is separated at once by the wing 

 venation, the definite wax-pore structures, and the long exserted 

 lingula. There are, however, forms of this type in general structure 

 which have an included lingula and wax pores tending toward those 

 of Paraleyrodes. For these forms we erect a subgenus, Metalewodi- 

 cus. This subgenus does not seem to be directly on the line toward 

 Paraleyrodes. It is, as far as wax pores are concerned, but the 

 lingula seems to place the group by itself. 



The genus Paraleyrodes is plainly derived from near Aleurodicus 

 by the reduction of the radius and part of the media, and by the short- 

 ening of the spinnerets and the cup of the wax pore. At the same 

 time some of the segments of the antennae have united. It is the most 

 specialized genus of the Aleurodicina? as Neomcislxllia is the most 

 specialized in the Aleyrodinae. The position of the family and the 

 relations of the genera, as we understand them, are shoAvn in figure 1. 



