6 PROC. ENT. SOC. WASH., VOL. 23, NO. 1, JAN., 1921 



against the epipharynx. Figure 7, showing the cicada's mouth 

 forced open, reveals the pharyngeal cavity beyond; when the 

 mouth is shut the only inlet to the pharynx is through the 

 narrow channel on the hypopharnyx. On figure 15 this channel 

 shows in section at Mth. 



The dilator muscles of the pharynx (PhyMcl} are feather-like 

 bundles of fibers attached to the front and inserted on stalk-like 

 tendons attached in a row along the median line of the pharyn- 

 geal roof. The latter collapses by its own elasticity when the 

 dilator muscles relax. The contraction of the muscles lifts the 

 roof, thus sucking the liquid food into the lumen of the pharynx 

 through the tubular mouth from the channel between the second 

 pair of sets. When the roof drops back, its lower end comes 

 down first and closes the mouth pore, preventing the liquid from 

 making its exit where it entered and, at the same time, forcing 

 it upward into the rear part of the pharynx and into a secondary 

 pharyngeal bulb (phy) located just over the tentorium (Ten}. 

 The lumen of this bulb is apparently dilated by muscle fibers 

 extending from its dorsal wall to the epicranium. From this 

 chamber^ the liquid is fed into the tubular oesophagus (ffi). 

 Both the stomach and the rectum of living cicadas are usually 

 filled, often tensely distended, with a clear liquid, even at the 

 close of their natural lives when their life functions are over. 



There are two large sets of salivary glands (fig. 15, G7) on each 

 side of the head. Their duct unites above the base of the 

 labium with the duct from the other side, and this common 

 duct appears to open at the very tip of the terminal point of the 

 hypopharynx. In the base of the hypopharynx it is connected 

 with the chamber of the salivary pump (SalPmp). The function 

 of this organ is supposed to be that of forcibly expelling the 

 saliva from the duct. The aperture of the latter is placed where 

 the saliva will enter the setal channel just where the latter opens 

 to the mouth pore. The saliva of Hemiptera is thought to func- 

 tion as an irritant or solvent in the tissues pierced by the setae, and 

 perhaps to have digestive properties as well. In the first case 

 the force pump is necessary to drive the -liquid down the setal 

 channel and into the punctured food tissue, but when this is 

 accomplished it would seem as if farther pumping would counter- 

 act the upward flow of the food liquid. Perhaps we do not 

 entirely understand the action of the salivary pump. Anyhow, 

 its piston is worked by two powerful muscles, the right one of 

 which (Mel} is seen in the figure. It is attached partly to the 

 tentorium and partly to a large plate entad to the occipital rim 

 of the head, and connected with the posterior braces of the 

 pharynx. 



The foregoing descriptions and the figures should make the 

 mere anatomy of the cicada's head and mouth parts reasonably 

 clear, and the work of other writers shows that the structure is 



