54: Annals Entomological Society of America  [Vol. VII, 
in the manipulation of the long buccal setz, the four apparently 
modified mandibles and maxillz, which are, in the case of this 
group of insects, extended into a long piercing beak. These 
four chitinous rods are arranged so that the plant juices pass 
up through the tube formed by their union. Attached behind 
the rostrum and lying free in the body cavity, is the setal 
pouch, extending well back towards the posterior end of the 
thoracic ganglion, into which the sete are pulled when they 
are not in use. 
At the base of the arcus inferior (Plate XIII, Fig. 11-b) 
is found a very interesting apparatus made particularly striking 
by its close resemblance to a piston valve, with all of its attach- 
ments, chamber, rod and head (Plate XIII, Fig. 12). Figure 
13 shows a diagramatic cross section of this valve, showing 
inlet, 13-i, from salivary glands (Plate XIII, Fig. 11-d) and 
outlet into oesophagus 13-o. 
Here again, in the impossibility of actual observation of 
the functioning, the interpretation of the actual function of 
the organ has to be based upon its structural make-up and the 
work that it apparently has to perform. Dr. Berlese is of the 
opinion that this pump is used for drawing the saliva from 
the large paired glands (Plate XIII, Fig. 11-e), and the arrange- 
ment of the ducts and the openings into the cylinder would 
seem to indicate this. Yet the rule for, most insects with 
comparable organs is that these glands, as a result of an internal 
pressure caused by a continual secretion of the cells from 
within, or from muscular action, force the juices out. In 
the case of this insect no muscles are to be found that could 
perform this function, and, from the make-up of the glands 
themselves, they seem to the writer to be admirably adapted 
to operate through a pressure formed from within. Again, 
from the make-up of the long, slender, four-pieced proboscis, 
it would seem to be impossible to pump saliva into the plant 
tissues, for pressure from the inside would disrupt the tube. 
Necessarily, therefore, if there is a passage of fluid down this 
setal arrangement it would have to be done with little or no 
pressure. The presence of stained plant tissue at the point 
of puncture possibly indicates that some fluid does pass, as 
exemplified by the familiar reddish staining occasioned by the 
presence of the San Jose scale (Aspidiotus perniciosus Comst.) 
