MORPHOLOGY OF THE ALEYRODIDjE. 13 
tance cephalad from the tip of the ovipositor. In Dialcurodiem it ap- 
pears to be very similar in shape, but in Aleurodicus it is narrower 
and more elongate, while in Paraleyrodes it is rounded. What ap- 
parently corresponds to the subgenital plate here is a large structure 
covering the caudal ventral portion and extending some distance 
dorsad on each side. The structure of the ovipositor is considerably 
like that found in the Psyllida?, while it differs quite markedly from 
the structure present in the Aphididse. It is composed of six pari . 
the outer covering of Avhich usually bears a definite number of hairs. 
These parts are grouped into pairs. The inner and upper pair of 
these is usually distinct for some distance, at least, and the parts are 
easily separable. The outer pairs, however, have grown together 
almost entirely and appear as one pair. Occasionally, though, they 
can be seen split at their tips, as is the middle pair, and they are 
sometimes sculptured or serrate. Extending throughout the ovi- 
positor there are a number of chitinized rods. These appear to be 
composed of parts jointed together and working one against another. 
There are present toward the tip flattened structures which appar- 
ently correspond to the " sting palpi " of the Psyllida?. The ovaries 
are two in number and very large. They are composed of five-cham- 
bered ovarian tubes and in some cases almost entirely fill the abdo- 
men. The receptaculum semincdis is ventral and the oviduct, coiling 
upon itself considerably, opens between the valves of the ovipositor. 
LEGS OF THE ADULT. 
The rudiments of the legs appear very early in the embryonic state, 
at about the same time as those of the mouthparts. A study of the 
legs of the adults is interesting, as it tends to throw some light on 
the position of the family. The three pairs are considerably alike, 
varying only in the relative lengths of the different segments. The 
femora and tibia? are elongate and armed with spines and hairs. The 
tibia? especially possess several longitudinal rows composed of 
prominent spines placed close together. On the distal third these 
become fewer in number, excepting for a comblike structure, which is 
found in at least several species. The distal end of the tibiae is sur- 
rounded by a number of short spines which, though much weaker, 
suggest the jumping spines of the Psyllida?. The tarsus is composed 
of two segments almost equal in length, and in this regard it is much 
closer to the Psyllida? than to the Aphididse, in which one segment is 
very much reduced, or to the Coccida? and some Aphididse, in which 
it is altogether lost. Attaching the claws and paronychium to the 
tarsus proper are a number of irregular pieces difficult to make out 
and which ma}' be part of the tarsus. The foot itself seems much 
nearer to that of the Psyllida? than to that of the Aphidida?, for the 
