POST-EMBRYONIC DEVELOPMENT OF CULEX. 17% 
quires a chitinous lining and dilator muscles and forms 
the organ for injecting the saliva into the wound. The 
soft parts within the mandible of the male appear to be 
completely absorbed and the imago has no mandible. 
The antenne arise in front of the compound eyes and 
are laid back on the sides of the thorax, their hinder ends 
being hidden by the wings. The cuticle shows a distinct 
but not obvious jointing, the basal joint being the largest. 
The pulpy tissues within rapidly shrink away from the 
cuticle and a new cuticle is formed within, clothed with 
small hairs in the female and with very large ones on the 
second to the thirteenth segments in the male. During 
this shrmking the segmentation of the imaginal antenne 
loses its correspondence with that of the pupal cuticle, the 
two terminal segments, which are devoid of long hairs, 
becoming much longer than the other thirteen. The basal 
joint or “‘ear’’ I will describe with the sense organs. 
The prothoracic siphons (dt. fig. 1) are nearly cylin- 
drical tubes, narrower at their bases and arising from a 
pair of slight prominences on the sides of the thorax. The 
outer surface is marked so as to give the idea of imbricated 
scales, each scale ending ina minute spine. The distal end 
of the tube is somewhat obliquely truncate and is notched 
on its inner side. ‘The inside of the tube is beset with 
numerous small curved spines, and the cavity communi- 
cates with the tracheal system. These organs are shed 
with the pupal cuticle, and their walls are almost all 
cuticle, the layer of epidermis and mesoblast, if there is 
any, is extremely thin, and Palmén’s statement (2) that 
the organ is a gill is absurd. 
The wings are plates of the form shown in fig. 1. They 
are fairly thick and the imaginal wings within them, 
while diminishing very greatly in thickness, increase 
largely in surface and so become much folded. They also 
