AKT. 23. BLISTER BEETLE TRICRAXIA PARKER AND BOVING. 15 



the mandibular condyle to the occipital foramen. Axis (an imagi- 

 nary line) between the dorsal and the ventral mandibular artic- 

 ulation ahnost longitudinal and horizontal, hence the plane of move- 

 ment perpendicular; no molar structure; inner edge from middle to 

 apex with a series of six tooth-like transverse ridges; the position, 

 the shape and the dentation of the mandibles enable the larva readily 

 to seize and keep a firm hold of one of the hairs of the host by press- 

 ing it against the hollow underside of nasale (figs. 4, 24). 



Maxilla, with cardo reduced (or fused with stipes). Stipes de- 

 veloped as an immovable, slightly convex plate, with suboval outline, 

 framed in by the bracon, by the anterior portion of tlie ventral mar- 

 gin of epicranium, by the triangular enlargement of the epicranial 

 margin, and by the posterior, lateral part of mentum.^ Stipes with 

 one small seta and one macrochaeta of same shape and extraordinai-y 

 length as the terminal antennal seta. Maxillary mala single, small, 

 semiglobose, fleshy, set with several medium long or short setae. 

 Palpus, three jointed, almost twice as long as stipes, slender, 

 straight, apically obliqueh' truncate; with few and minute setae; 

 basal joint small, cylindrical, about as wide as mala, somewhat 

 shorter than wide; second joint cylindrical, somewhat narrower than 

 the basal joint, and three times longer; apical joint as long as basal 

 and second joints together, clavate, terminally truncate, somewhat 

 naiTower than the second joint. 



Submentmn and mentum, fused into a single approximately pen- 

 tagonal region which is broad in front, attenuate behind, and within 

 the posterior corner marked on each side by a narrow, bow-like chiti- 

 nization; anterior margin concave, as wide as labium; each antero- 

 lateral margin concave, half as long as the anterior margin ; each pos- 

 tero-lateral mai-gin twice as long as the anterior margin ; entire re- 

 gion slightly chitinized, flat medianly, longitudinally depressed, 

 probably offering a convenient resting place for the hair of the bee- 

 host when it carries the larvae to its nest. One pair of medium long 

 setae at middle of mentum. 



Labium, a semicircular region, about one third as long as one of 

 the maxillary stipites; posteriorly limited by a bow-shaped chitiniza- 

 tion which carries one pair of punctures (or possibly minute setae). 

 Palpigers chitinized ; each occupying one fourth of the entire ventral 

 labial region. Palp two-jointed, small, as long and half as wide as 

 palpiger; basal joint cylindrical, hardly one third as long as entire 



» A slightly chitinized narrow arm extends from the triangular enlargement of epicra- 

 nial margin, passes along the posterior lateral part of mentum to the anterior free part 

 of mentum and fuses here with the rod-like chitinous thickening, or bracon, of the buccal 

 membrane between the ventral mandibular articulation and the hypopharynx. Thus the 

 base of the maxilla is completely surrounded by a chitinous ring, which consists of the 

 same anatomical elements as in the StaphyHnini and the Melandryidae. 



