12 CLASSIFICATION OF THE ALEYRODIMl. 
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 Psyllidse, 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 persece it appears bifurcate. It is an elongate, 
subcjdindric 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 Psyllidse. 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 ductft At this place 
of union are found the openings of the ducts leading from the two 
large sac-shaped structures, in all probability the glandulne mucosa?. 
The external genital organs of the male are definitely formed in the 
pupal stage and fairly early in this stage the claspers can be seen 
fully shaped. They are developed, according to Cary, 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 (iENITAL ORGANS. 
The supragenital segment in female Aleyrodidse shows some varia- 
tion in form. In Alcyrodcs 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- 
