726 MR. P. R. AWATI ON THE MECIANISM 
distance as a solid rod of chitin. To this the pump muscles 
are attached. This structure constitutes the piston and the 
handle, the swollen portion being the piston and the backward 
continuation the handle. The latter is flattened dorso-ventrally. 
(ii.) The efferent salivary duct.—This is a long and narrow 
duct, issuing antero-dorsally from the pump-chamber. It has 
a very narrow lumen and runs through the pump-stem and 
perforates the hypopharynx before it opens anteriorly into the 
ejection-canal. It has been shown above that the pharyngeal 
duct also runs through the same region of the hypopharynx on 
its way to the suction-canal. These ducts are thus brought 
together and connected with one another by the hypopharynx. 
Jt is the only connection between them; otherwise they are 
distinct from each other. They do not communicate with one 
another. And yet there are many misrepresentations about it. 
Many of the previous writers are very doubtful of the facts, and 
do not seem to know whether the efferent duct runs straight 
into the ejection-canal or the labial groove, or opens into the 
pharyngeal duct. Muir and Kershaw (22) write: ‘“ The syringe 
or salivary pump. . . opens on the basal part of the labium 
beneath the hypopharynx.” This statement is too vague to be 
eriticised. According to them, it seems that the efferent salivary 
duct opens into the labial groove. The same mistake has been 
made by Grove (16), and is also found in many text-books. The 
efferent salivary duct opens neither into the labial groove nor 
into the pharyngeal duct, but, on the contrary, runs straight into 
the ejection-canal and opens there. In short, the ducts, pharyn- 
geal and efferent salivary, are separate from one another and 
open into the suction- and ejection-canals of the maxillary stylets 
respectively. (Text-fig. 10, Su.C., E.C.) 
The efferent duct is supported by 
(i.) The pump-stem, and 
(ii.) The hypopharynx. 
It runs a considerable distance into the ejection-canal before 
it ends. This prevents its slipping out of the canal when the 
maxille are pushed down by their protractors. (Cf. pharyngeal 
duct.) 
(iv.) The afferent salivary duct.—The two salivary ducts issuing 
from the reservoirs on either side come together in the head and 
form the afferent or common salivary duet under the brain. 
This afferent duct is seen, in median longitudinal sections, 
running underneath the pump-cylinder and. opening antero- 
ventrally into the pump-chamber. It has a lumen bigger than 
that of the efferent salivary duct, and its walls are flexible and 
elastic. There is not a trace of a valve at its entrance into the 
pump-chamber. 
The salivary ducts (text-fig. 7, $.D.)—There are two salivary 
