Pratt LXI 
THE HOG LOUSE, HAEMATOPINUS SUIS LINNE 
1, Transverse section through stomodaeum at anterior level of attachment of basal part of ‘‘mandibles”’ 
of Enderlein to lateral wall of head (a, buccal plate; b, dorsal element of piercers; c, salivary duct; d, ventral 
element of piercers) ; 2, transverse section through stomodaeum at anterior level of ‘‘ mandibles ” (e, pump- 
ing pharyngeal tube; other lettering as in 1); 3, transverse section through stomodaeum at posterior level 
of ‘‘ mandibles ’’ (lettering as in 1 and 2); 4, transverse section through stomodaeum in posterior region of 
buccal plate (aa, posterior arms of buccal plate; f, ridge on dorsum of pumping pharynx; other lettering 
as in 1 and 2); 5, transverse section through stomodaeum in region of-anterior dorsal chitinous plate (g, 
pumping pharynx; h, piercer sheath; other lettering as in 1); 6, transverse section through stomodaeum 
immediately behind anterior chitinous plate (ii, tendons of dorsal retractors of buccal plate; other lettering 
as in 5); 7, transverse section through stomodaeum just after its separation from piercer sheath (lettering 
as in 6); 8, transverse section through anterior region of pharynx (k, pharynx); 9, transverse section through 
posterior region of pharynx behind first dorsal chitinous plate (jj, hollow tendons of central elevator muscles; 
k, pharynx) 
. (All drawings on this plate made with oil immersion and drawn to scale) 
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