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pharynx. The labrum is blended with the epipharynx, 
but does not extend to the tip. 
The hypopharynx .—Is a thin, flat two-edged lamella 
closely applied to the under surface of the epipharynx. 
It is pierced by the salivary duct down which the 
salivary secretion and sporozoits pass. The opening 
of the duct is continued as a groove reaching almost 
to the tip of the hypopharynx. 
Fig. 52. Showing relation of Pharyngeal and Salivary Pumps to the 
Proboscis 
The mandibles .—Are very fine chitinous rods, in 
cross section crescentic in shape. At the tip of the 
mandibles are about thirty serrations, though in certain 
species of Culex these appear to be absent. 
The mandibles are closely applied to the sides of 
the epipharynx. 
The maxillae .—Are stouter than the mandibles, 
and fit around the outer side of these and the hypo- 
pharynx. They have about twelve serrations at the 
extremity, coarser than those of the mandibles. In 
some Culices, papillae replace the serrations. 
The Maxillary Palps .—These lie upon either side 
and somewhat dorsally to the proboscis. In the act 
