102 Psyche [June 
to the base of the seta. A short upwardly directed one is attached 
behind the ocelli, a longer one extends posteriorly and is attached 
laterally to the walls of the occipital foramen. The protractor 
muscle (pm) is attached to the inside of the frons. This muscle 
instead of being directly attached to the base of the mandible, is 
attached to a small chitinous triangular plate (b) which articulates 
at one corner with the gena near the anterior margin of the latter 
just anterior to the base of the antenna. This triangular plate 
likewise articulates with the mandible by means of a small rod (a) 
which is attached at its posterior end to the base of the mandible, 
while its anterior end articulates with the ventral corner of the 
triangular plate. The muscle in contracting pulls the mandible 
forward by means of the small connecting rod. These protractor 
and retractor muscles control the piercing and probing of the max- 
illary setee, and the piercing and holding of the plant tissues by 
the mandible. 
The cavity of the pharynx (ph), which is larger in the middle 
than at either end, becomes continuous with that of the suction 
canal, in the sete, at the point of divergence of the maxillary sete. 
At this point the hypopharynx (hph), see Pl. 2 f. 12, or anterior 
portion of the ventral plate of the pharynx (which is a slender 
chitinous trough-shaped process) enters the suction canal and lies 
on the ventral floor of the latter, while the epipharynx, or anterior 
portion of the dorsal plate of the pharynx, lies above the sete, 
fitting snugly over them, and extends anteriorly between the 
lobes of the clypeus. The membranous sheath surrounding the 
union of the pharynx and sete make this union air tight. 
The pharynx becomes constricted posteriorly as it passes be- 
tween the circumcesophageal commissures, opening posteriorly into 
a membranous cesophagus. Posterior to this constriction the 
oesophagus is enclosed by a sheath made up of longitudinal muscles. 
This sheath is connected with the wall of the occipital foramen 
dorsally by two transversely attached muscles, given off dorso- 
laterally from the muscular sheath, and ventually it is connected 
by two ventro-lateral muscles which diverge and are attached to 
the walls of the occipital foramen. This sheath extends from the 
posterior end of the pharynx back into the prothoracic region. 
The four muscles support the cesophagus in this region and 
probably by their movements of relaxing and contracting, together 
