6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
The CORPOROTENTORIUM (ct) is located in the center of the head 
and is transverse in shape. 
HEAD APPENDAGES 
The movable parts of the head are the antennae, labrum, mandibles, | 
maxillae, hypopharynx, and labium, 
The ANTENNAE (ant) are setiform and about equal in length to the 
length of the head. Each antenna is composed of seven segments. The 
basal segment or scape (s) is short and thick and located in the medio- | 
ventral portion of a circular membrane that is bounded by the antennal 
sclerite. The second segment or pedicel (p) is longer than and about 
two-thirds the diameter of the scape. It narrows abruptly distally to 
meet the flagellum ({), which is about one-half the diameter of the 
pedicel. The first, third, fourth, and fifth flagellar segments are sub- | 
equal in length and each is approximately one and one-half times the 
length of the second segment. The terminal or fifth flagellar segment | 
tapers apically to a fine point. Each segment of the antenna bears © 
several long light-colored setae. 
The LaBruM (lm) or upper lip is movable and, though not a true : 
appendage, complements the other mouthparts. It is a transverse, 
reniform sclerite suspended from the clypeus by a narrow strip of | 
membrane. The dorsal and ventral margins are parallel, the dorsal 
margin being produced while the ventral margin is emarginate. The | 
anterolateral tormae extend into the membranous region at the base — 
of the labrum but do not articulate with the clypeus. With the ex- 
ception of a small bare subtriangular dorsomedial area, the anterior | 
surface bears numerous short spiniform setae. In addition, many — 
long setae are present on the distal margin. | 
The MANDIBLES (md) are well developed and lie horizontally in the 
space between the labrum and the hypopharynx. Each mandible has 
its mesal surface differentiated into a distal toothed incisor area (in) — 
and a proximal molar surface (mo). The right mandible bears three © 
sharp apical teeth on the incisor lobe, apparently for tearing the food, 
and three heavily sclerotized, blunt teeth on the molar surface. The | 
left mandible is identical in size to the right mandible but differs | 
slightly in dentition. The former has the ventral incisor tooth apically — 
bicuspidate and the proximal molar tooth lacking. | 
The base of the mandible is triangular in outline. Each mandible | 
articulates dorsally on the base of the clypeus and ventrally, by means _ 
of a conspicuous condyle (co), on the lower margin of the cranium. | 
A strong adductor tendon (adt) is attached to the inner angle of the 
