100 Psyche [June 
the gula (gu). The clypeus, as has been stated, is fused at its 
base with the frons, and at this point is narrow, but as it curves 
forward and downward it widens at its tip to form the base of 
attachment for the labrum (Ibr) from which it is separated by a 
narrow membranous ring. 
The labrum is an elongate triangular sclerite. Its anterior sur- 
face is convex, while its posterior surface is flat and contains a 
groove which lies above the groove on the basal half of the anterior 
surface of the labium (lab). 
On either side of the clypeus is a narrow prolongation of the 
frons called the fulerum (fr). The fulera lie close to the lateral 
walls of the clypeus hiding them, but not united with them except 
at their bases, where they fuse with the head capsule. 
The maxillary laminz (Im) lie below the base of the antennz 
(ant). Their bases are fused with the gene and their ventral mar- 
gins are united with the buccule (bu), which are chitinous plates 
projecting from the anterior ventral side of the head on either side 
of the base of the Jabium. 
The labium articulates with the anterior ventral region of the 
head between the buccule. The labium contains, as stated above, 
a dorsal groove in which lie the setz (s). The edges of the groove 
beyond, or distal to the overlying labrum, overlap, forming a closed 
tube, thus giving the enclosed setz more support. At its basal 
end the groove becomes very shallow; the labium becomes filled 
with muscles, tracheze and nerves, and the sete in this portion of 
the labium gradually come to lie within the labrum, whose edges 
meet beneath and confine the sete. 
The sete now pass back through the articulating membranes, 
which lies between the labrum and clypeus and between the lateral 
walls of the clypeus. The walls of the clypeus at its tip turn under, 
and their edges interlock, forming a narrow pair of supporting 
lobes above which the sete pass. Upon emerging from these 
lobes the maxillary setz (m) spread apart to receive the tip of the 
pharynx and the canal from the salivary pump, both of which 
enter the set at this point. 
The setze represent the mandibles (md) and the maxille (m). 
The maxillz are fluted and interlocked so as to form two tubes, 
namely the upper or suction canal (fc), and the lower or salivary 
canal (sc), see Pl. 1 f. 2. The mandibles are slightly shorter than 
