30 Journal of the Asiatic Society of Bengal. [N.S., XIX, 
ceptacle C. The receptacle duct seems to conduct the extra 
saliva from D to the receptacle C, from which the saliva can 
flow back if necessary. The salivary duct proper (S.D. 
afferent salivary duct (A.S.D., Figs. 9 and 13) starts from 
the reservoir (C) and passes forwards as a white thick walled 
tube, and enters the head region running parallel to its fellow 
of the opposite side. Ultimately both these tubes converge 
and di-charge their contents through a common opening into 
the salivary pump chamber. This opening situated in the 
antero-ventral region of the salivary pump chamber seems to be 
guarded by a valve which opens inwards into the cavity of the 
chamber, thus preventing the saliva from flowing back. The 
ducts do not appear to unite to form a common afferent sali- 
vary duct. 
The salivary duct has a thick chitinous rains external e 
which lies a distinctly nucleated cellular laye Both t 
reservoir and salivary ducts are surrounded se siieat aurendl: 
so as to keep them distended. 
The salivary pump (Figs. 9 and 13) is a minute cylindri- 
cal organ lying under the pharyngeal duct, where the diverging 
stylets enter the head capsule. It is su pported laterally by the 
arms of the tentorium (Figs. 6 and8). The pumpchamber prop- 
er (P.C.) is chitinous and almost rectangular in shape. The 
afferent salivary ducts enter it by an opening in the antero-ven- 
tral — whilst the etferent salivary duct (E.S.D.) leaves it 
y an opening situated in the upper region of the anterior wall. 
The posterior wall of the rectangular chamber is thin and flexi- 
ble except in the centre where it is highly thickened and 
chitinized to form the head of the piston (Pi), which is produced 
backwards into a stout bar-the piston-handle-connected to the 
occipital wall of the head by means of two series of powerful . 
muscles (Pi.M.). When the latter contract, the piston is drawn 
back, increasing the size of the chamber with the result that 
saliva flows in from the afferent ducts. When the piston re- 
turns, the saliva, owing to the increasing pressure, flows out by 
the efferent duct. This duct is supported by a grooved pro- 
longation of the anterior wall of the pump chamber, known as 
the pump stem (P.S.) The latter supports below the afferent 
duct and above the pharyngeal duct, carrying these, one over 
the other, to the ejection and suction canals respectively. 
Thus the saliva does not pass to any part of the alimentary 
canal, but is conducted by the ejection canal directly into the 
plant tissue. 
As to what is the real hypopharynx. seems to be a debat- 
able point. Muir and Kershaw (13) regarded the terminal por- 
tion of the pharynx as the hypopharynx, and the ventral wall of 
the pharynx as continued forward to form the spoon-shaped end 
of the hypopharynx. Tower (28) held a similar view. Awati (1), 
on the other hand, considered the anterior region of the pump 
eo) 

