DYNASTIN.E 143 



Section A. 



The species of this division are moderately numerous and are 

 distributed from the Atlantic coast to southern California and 

 northern Mexico; they are resolvable into two remarkably differ- 

 entiated groups, as shown by the table given below. The pronotum 

 is, like the elytra, almost uniformly immaculate, but in villosa 

 there is occasionally a complex nubilate design, which is com- 

 pletely analogous to the faint intricate design seen on the pronotum 

 of fulgurata, belonging to the second group of the genus, indicating 

 that, in spite of the marked differences in the antennae as modified 

 by sex, there is really but a single genus. Our species may be 

 recognized quite readily as follows: 



Male and female very different in general habitus, the female shorter, 

 stouter, generally darker in color, smaller in size, with thicker integu- 

 ments and stronger sculpture than the male and always having a 

 feeble medial dilatation of the lateral edges of the elytra; pygidium 

 with erect pubescence in the male, glabrous in the female 2 



Male and female similar in form, the latter generally somewhat darker 

 in coloration and of larger size as a rule but without marginal modi- 

 fication of the elytra, the pygidium glabrous in the male or virtually 

 so; species Sonoran, so far as known; individuals of both sexes 

 varying greatly in size of body, as in the preceding division 8 



2 Elytra glabrous in both sexes, the female without long hairs along the 

 lateral edges 3 



Elytra sparsely pubescent, the pubescence very conspicuous (cf) but 

 almost wanting ( 9 ) ; female elytra with long bristling hairs along 

 the sides 7 



3 Body (cf ) subcylindric, perfectly parallel, the prothorax fully as wide 

 as the elytra, convex, shining, pale rufous, the head black basally 

 and the elytra pale brownish-flavate; head sparsely punctate, rather 

 more than half as wide as the prothorax; clypeus transverse, semi- 

 circular, with the sides anteriorly broadly oblique and straighter, 

 all the edges strongly reflexed; surface strongly but not densely 

 punctate, the suture obsolescent medially; antennal club much 

 longer than the stem; prothorax two-thirds wider than long, the 

 feebly arcuate sides converging anteriorly, the basal angles rounded, 

 the apical sharp but rather short; basal bead wholly wanting, the 

 apical entire; punctures strong, sparse, a little closer laterally; 

 scutellum with scattered strong punctures, the edges abruptly and 

 broadly smooth; elytra a fourth or more longer than wide, the 

 parallel sides very feebly sinuate before the middle, the apex rapidly 

 circularly rounded; punctures variable, rather coarse to fine, always 

 finer posteriorly, the three geminate series usually evident; pygidium 

 shining, convex, finely, very sparsely punctate, the hairs rather short 

 and very sparse; hind tarsi two-thirds longer than the tibiae; claw- 

 joint of the anterior tarsi about as long as the three preceding. 



