394 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
Now, if these separated parts be put together again we get a pretty 
clear idea of how the cicada takes its food. The setae {1 Set and 2 
Set) , normally lie deep in a groove along the front side of the labium 
(Lh), which groove, of course, does not show in the drawing made 
from the side. The upper ends of the setae have arms extending into 
the head cavity which have two sets of muscles attached to them — 
Fig. 5. — Showing the anatomy of the head of an adult cicada (7 times natural size). 
A, First side plate of head ; a, attachment of hypopharyux to the head ; Ant, antenna ; 
B, second side plate of head; 6, lower lobe of B ; c, appendage of b; Clp, clypeus ; 
E, compound eye; c, roof of the pharynx; Ft, front; Ilpliy, hypopharynx ; Lb, labium; 
Lm, labrum ; mh, neck membrane; Mtli, mouth; O, simple eyes or ocelli; 1 Set, first 
seta ; 2 Het, second seta. A, The mature head with the parts in natural position. 
B, Soft head of a transforming adult with the parts separated, showing the mouth 
(MtJi) wide open, the tongue or hypophai-j'nx (Hphy) suspended behind it, and behind 
the tongue the setae (Set) inserted into pouches of the head. Only the left setae are 
shown. In the normal liead (-1) they are concealed in a groove on the front side of 
the labium (L6). 
the fibers of one set, going up to the top of the cranium, draw the 
setae up by contraction; those of the other, coming down and side- 
ways from the tops of the arms to the inner faces of the head plates 
A. and B^ push the setae out when they contract. Thus, by these 
muscles, the tips of the setae can be worked in and out at the end of 
the beak and made to pierce the bark of the tree. As they enter, the 
labium (Lb), which incloses them like a sheath, can be drawn up 
into the flexible membrane (mh) at its base, so that the setae can be 
