12 CLASSIFICATION OF THE ALEYEODIDiE. 



the subgenital plate and has been produced by the fusion of the upper 

 margins of that plate, while the lingula, as explained elsewhere, rep- 

 resents the supraanal plate. This would seem suggested from the 

 state of affairs found in the Psyllidae, for in comparing Psylla sp. 

 (PL II, fig. 6) and Aleurodicus sp. (PI. II, fig. 7) it will be seen that 

 the genital segments are very similar. If in the psyllid the upper 

 margins of the subgenital plate were united above the claspers and 

 the supraanal plate reduced, they would be almost identical. In any 

 case, however, the close relation of the two families seems indicated 

 by this structure. The shape and armature of the claspers vary con- 

 siderably in different species, but as a rule these organs are curved at 

 the distal end and armed with a number of spines. Those of comata 

 are very hairy and psyllidlike. Each clasper generally has on the 

 outer margin of its distal part a rounded shoulder and its distal end 

 is formed into two processes for the attachment of the muscles. The 

 copulating organ is found between the claspers. It is usually single, 

 but in Paraleyrodes persecR it appears bifurcate. It is an elongate, 

 subcylindric rod, tapering on its distal part and swollen at the base. 

 In some forms it appears grooved on its upper surface for the recep- 

 tion of the penis, but in others we are not able to make this out, but 

 the two seem fused into one structure. The penis is carried recurved 

 toward the vasiform orifice in a manner very similar to that found in 

 the Psylliclae. The ejaculatory duct extends cephalad some distance 

 from the base of the penis, where it has its origin in the union of the 

 two vasa deferentia. 



The testes (PI. II, fig. 1) are globose or elongate bodies situated 

 one on each side of the median line of the abdomen. The vas 

 deferens^ in leaving the testis, is coiled upon itself and then swollen 

 considerably to form the seminal vesicle. Again contracting, it is 

 united with its fellow and forms the ejaculatory duct. At this place 

 of union are found the openings of the ducts leading from the two 

 large sac-shaped structures, in all probability the glandula3 mucosae. 

 The external genital organs of the male are definitely formed in the 

 jDupal stage and fairly early in this stage the claspers can be seen 

 fully shaped. They are developed, according to Gary, from the two 

 pairs of posterior abdominal imaginal disks. The reproductive or- 

 gans can be seen in all the larval stages as a pair of gland-like masses, 

 one on either side of the abdomen. 



FEMALE GENITAL ORGANS. 



The supragenital segment in female Aleyrodidas shows some varia- 

 tion in form. In Aleyrodes it is broad and crescent-shaped and is 

 armed with regularly placed hairs. It is often differently pigmented 

 from the surrounding portions of the body and is situated some dis- 



