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Explanation of Figures 
Plate IV 
All figures drawn with camera lucida. 
Fig. 1. Outline of head and tentorium from the ventral side. X 160. 
a.s. The first segment of the antenna, a.t. The anterior arm of the ten- 
otrium. c.m. The chitinous supports of the mandibles, e. The eye. 1. The 
labrum. m. The mandibles, m.f. The maxillary fork. m.m. Mandibular 
adductor muscle, o.s. The oesophageal sclerite. p.t. The posterior arm of the 
tentorium. 
Fig. 2. The Mandibles. X 250. 
a. The right mandible, b. The left mandible, a.ab. The point of attach¬ 
ment of the abductor muscle, a.ad. The point of attachment of the ad¬ 
ductor muscle, m.p. The pivotal knob which fits into the head capsule, m.s. 
The molar surface of the mandible, v.p. The ventral points of the mandible. 
Fig. 3. Enlarged view of the cells of the right labial gland. X 930. 
n. The nucleus, nu. The nucleolus. 
