210 Mr Harrison, A preliminary account of the 
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lumen of the tube thus formed enter the dorsal and ventral 
piercers, and the salivary duct. | 
Some of the interpretations which have been placed upon the — 
structures thus briefly indicated will appear in the more detailed 
descriptions that follow. I treat the structure and functions — 
together for each of the several parts which have been enu-— 
merated; and follow this by a recapitulary account of the whole 
process of feeding, with the combination of functions involved. — 
The mouth and buccal cavity. 
In the position of rest, the mouth is an oval aperture, with | 
longer diameter transverse, absolutely terminal. It is surrounded — 
dorsally and laterally by loosely folded integument. It leads into ~ 
the approximately cylindrical buccal cavity, on the dorsal wall of — 
which, just inside the mouth, are two closely apposed chitinous — 
plates, bearing a number of recurved denticles. At their proximal 
ends these dental plates are loosely hinged to the buccal plate, a 
Fig. 1. Isolated buccal plate of larva, dorsal. 
thick chitinous structure which lines the roof and lateral walls of 
the cavity, and which is thickest dorsally, gradually thinning out 
as it approaches the floor. Fig. 1 shows a dorsal view of this 
structure as it appears in a moulted cast; and it is shown in 
Fig. 2. Transverse section through buccal cavity just behind mouth. 
Diagrammatic. 
section in Figs. 2 and 3 (bp.). At the posterior end of the 
buccal cavity this plate divides about the pumping-pharynx, in 
