A. D. Peacock 
103 
(1) Protractors , two pairs: (a) dorsal, (b) ventral. They serve to bring 
the buccal funnel forward for feeding, (a) Each dorsal muscle ( d.b.pr 
Text-fig. Ill) has its origin in the chitin of the anterior dorsal region of the 
clypeus. Its insertion is along the dorsal surface of the process but it does-not 
quite attain the posterior extremity of the process, (b) Each ventral muscle 
(v.b.pr., Text-fig. Ill) takes, a similar course to the dorsal but ventrally to the 
process. Its origin is in the chitin of the anterior ventral region of the clypeus 
and its insertion along the ventral surface of the process. (2) Retractors , one 
pair. Their function is to retract the buccal funnel after feeding. Each 
muscle ( b.r ., Text-fig. Ill) is short, thick, and arises from the lateral chitin 
of the clypeus. There does not appear to be any one area of insertion as the 
muscle seems to finish as a fascia sheathing the arch anteriorly. 
Pumping-pharynx (pp., Text-fig. Ill and PI. YI, fig. 1). This is a bladder 
of thin chitin, pear-shaped when dilated, of relatively large capacity, lodged 
within the processes of the buccal funnel and retained in position by several 
muscles. Its dorsal chitin is collapsed when the insect is not feeding. Its 
narrow anterior end succeeds the buccal funnel and at its posterior end is a 
constriction leading to the pharynx. Where the posterior constriction begins, 
setae are present on the floor and sides. The function of the setae (PI. VI, fig. 1) 
is a matter of conjecture 1 . The muscles are dilators and retractors but some 
seem to act both as dilators and protractors and one acts as dilator and 
retractor. (1) Medial dilator-protractors (m.d.pr., Text-fig. Ill and PI. VI, 
fig. 1)—four pairs. The origins of these muscles are in the roof of the clypeus 
near the middle line and they follow one another closely. The muscles run 
almost longitudinally, near the middle line, and their insertions, which succeed 
each other closely, are in the roof of the pumping pharynx near the middle line. 
(2) Dorso-lateral dilators (d.-l. d.) —three pairs, anterior, median and 
posterior. Each originates from the dorso-lateral chitin of the head and runs 
downwards and transversely to its insertion in the roof of the pumping- 
pharynx. The anterior pair runs down from the posterior dorso-lateral chitin 
of the clypeus, in the transverse plane, to their insertions on either side of the 
middle line and close behind the arch of the buccal region. The second pair 
also runs down in the transverse plane from the dorso-lateral chitin of the 
head, where the clypeus and epicranium meet, to their pumping-pharyngeal 
insertion which is a short distance behind that of the anterior pair and 
external to the dilator-protractor insertions. The third pair runs downwards 
and anteriorly from the dorso-lateral chitin of the anterior of the epicranium 
to their insertions at about the widest part of the pumping-pharynx and 
external to the insertions of the dilator-protractors. (3) Dorsal retractort 
( d.r ., Text-fig. Ill and PI. VI, fig. 1)—one pair. These are long muscles wit! 
1 The setae recall the bunches of retrograde hairs protruding into the lumen of the alimentary 
canal in mosquitoes at a point where the pharyngeal pump joins the oesophagus. See Nuttall and 
Shipley (Jonrn. Hygiene, 1903, vol. hi, p. 198, PI. VII, figs. 4 and 5), who ascribe a sieve-like 
function to these hairs.—E d. 
