102 
Mouth parts of Pedi cuius 
Anteriorly the sac tube partially embraces (1) the pumping-pharyngeal tube, 
and, beneath this, (2) the upper stabber with the salivary pipe and (3) the 
lower stabber. The pumping-pharynx sucks blood into the pumping-pharyngeal 
tube. The pharynx may fill and empty three times per second but probably 
the rate varies greatly. 
MORPHOLOGY IX DETAIL. 
The structures are described in a resting position but with the haustellum 
protruded slightly. 
Food Canal. 
Mouth. The anterior chitin of the head from which the haustellum projects 
is somewhat thin and loose. The haustellum is hood-like, with a thick base 
and with a mid-ventral slit, the buccal slit. The chitin of the rim is thin 
and is continuous with that of the buccal region. Anteriorly the buccal 
region is made up of two lateral concave dental plates, each bearing eight 
teeth. The chitinous teeth are placed five laterally and three dorso-laterally 
on each side. Each resembles a parrot’s beak and appears to be based on 
fibrous tissue. The chitin between the dental plate and the buccal funnel is 
thin and permits them a certain freedom of movement. When the haustellum 
is protruded slightly the structures surrounding the mouth are: (1) dorsally 
and laterally, the buccal funnel (buccal plate of Harrison); (2) ventrally, a 
floor of chitin continued inwards from the external ventral chitin of the head; 
(3) the paired buccal festoons which lie just above the floor and are closely 
approximated in the mid-ventral line. 
In the same transverse plane as the base of the haustellum are the buccal 
festoons. Each buccal festoon is a thick bar of chitin curving from the mid- 
ventral line obliquely outwards, backwards, and upwards to fuse with the 
lateral chitin at the front of the head. The function and significance of these 
structures is uncertain. 
Buccal funnel. (PI. VI, fig. 4.) This is a strong chitinous structure, 
about one-third the length of the head, shaped like a concave capital A with 
the letter solid above the bar, the point anterior, the concavity facing ventrally 
and the limbs diverging posteriorly. The anterior arched region forms the 
roof and sides of the beginning of the food canal and anteriorly it is hinged 
to the dental plates. The processes of the arch, which are longer than the 
arched portion, are longitudinally grooved for part of their inner length but 
the grooving disappears as they taper backwards. The grooved portions 
form part of the sides of the pumping-pharynx. When the pumping-pharynx 
contracts posteriorly the processes leave it. The arch is covered by membra¬ 
neous tissue and is slung anteriorly in the middle line from the roof of the head 
by strands of similar tissue. The processes serve for the insertion of various 
muscles. 
The muscles associated with the buccal funnel are the protractors and 
retractors (PI. VI, fig. 1 and Text-fig. III). 
