114 NEOTROPICAL PSELAPHIDAE 



and the cordiform pronotum has rounded lateral margins, with the lateral 

 foveae on each side not visible from a dorsal view. 



Certain special features of their anatomy should be noted, and are figured 

 for the genotype and related North American species in the plates (PI. IV, 

 XI, XII). The head varies in outline from subtriangular, in which the sides 

 are oblique, to the attenuated anterior end with a subtruncate front, to sub- 

 quadrate. In the subquadrate head the males have the sides more or less sud- 

 denly dilated anteriorly [parmata, ventricosa) . Although the front is usually 

 not prolonged, in some species {clypeata and jleutiauxi) the front is prolonged 

 above the epistomal region, strongly in males and less strongly in females. 

 The eyes are large and prominent. Two vertexal foveae are present between 

 the eyes, these foveae being nude, circular, and connected by an arcuate sulcus 

 which is usually well formed but may be partially interrupted. The ventral 

 surface of the head is provided with distinct capitulate setae. Maxillar>' palpi 

 four-segmented; first minute; second arcuate, slender basally and inflated 

 apically; third short, transverse, subtriangular, as wide as or wider than sec- 

 ond; fourth longest and widest, elongate-oval to subsecuriform. Antennae 

 eleven-segmented, with the first two segments larger than the third to seventh, 

 the second larger than the first; third to tenth inclusive small, with some 

 variation in shape and relative size among the species ; tenth segment usually 

 transverse, lenticular and bilaterally symmetrical but may be transversely tri- 

 angular and asymmetrical {clavata) ; eleventh segment quite large, conoidal or 

 ovoid, acuminate, provided with antennal cones which can be discerned only 

 in slide mounts at high magnification. 



Pronotum obcordate to cordiform, with rounded lateral margins, and the 

 basal third crossed transversely by an arcuate to biarcuate variably developed 

 sulcus; this sulcus continues down each pronotal flank to end in a lateral 

 fovea near or on the flanks of the prostemum, making the foveae invisible from 

 above; disc of pronotum simple. 



Elytra with the humeri never dentate, usually rounded, but in some species 

 nearly square {parmata, ventricosa, eggersi) ; there is no subhumeral fovea and 

 no subepipleural sulcus on the elytral flank; on each elytral flank, however, 

 there is an important generic feature in the presence of a fine oblique line 

 which extends from near the middle of the lateral margin obliquely to the elytral 

 apex. (In the North American Dalmosella and Trimiomelba, this cariniform 

 line is not oblique, but is parallel to the elytral margin from its origin at basal 

 third to apex, and forms a good criterion for separation ; this feature was known 

 to Casey in the erection of his melbaform genera.) Each elytron with two 

 basal foveae; the sutural gives rise to a sutural stria, and the discal gives rise 

 to a short variable dorsal depression. The abdomen has five subequal tergites, 

 the first tergite not narrowed at base ; the stemites show sexual differentiation, 

 there being six sternites in the female and seven stemites in the male. The 

 male seventh stemite is a circular, simple, uncarinated one-piece pygidium 

 which is asymmetrically articulated. 



Prosternum simple, with no median longitudinal carina. The mesosternum 



