H. C. FALL 407 



puzzling amount of variation, but of!"er no constant salient cliar- 

 acters by which I can separate them specifically, although it is not 

 unlikely that a nunil)er of distinct though v(n-y closely allied 

 species are involved. In the t^'^pe the eyes are a little more dis- 

 tant than the vertical width of their upper lobes, while in a male 

 from Oracle, Arizona, the distance apart is obviously somewhat 

 less than the width of the upper lobes, but this distance does not 

 hold constant in any group of specimens from one locality', the 

 variation Ijeing sufficient to baffle any attempt at separation on 

 this basis. The Nogales specimens look somewhat unlike the 

 San Bernardino ^Mountains type series, the markings are darker, 

 the sides of the prothorax a bit more strongly rounded, but these 

 characters are, I think, of little or no consecjuence, nor can I find 

 any others that are constant. The Williams males are like the 

 Nogales ones and the sole female is not distinguishable in any 

 way from the San Bernardino Mountains females. The Santa 

 Rita Mountains specimens are rather more densely punctate — 

 as a group — than any other series of specimens before me, but 

 other examples from one locality or another approach them in 

 this respect. Mohilis is, on the whole, quite close to quadratus, 

 but the two species are, I believe, capable of separation by the 

 tabular characters. 



89. Pachybrachys delumbis new species 



\'ery closely allied to mobilis; sculpture virtually the same, size a little smaller, 

 ej'es a little closer, more noticeably so in the female, in which they are sepa- 

 rated by two and one-fourth to two and one-half times the length of the basal 

 antennal joint; front claws of male only shghtly larger than the others, and 

 scarcely more noticeably so than in the female. In the male type the vertex 

 spot is large, but the frontal spot is narrow and the front is mostly yellow; the 

 thoracic M is cjuite distinct, attaining the apical third, the thorax predomi- 

 nantly yellow. Elytral spots rather small, the outer series and the posterior 

 inner one distinct, two anterior spots of the inner series not defined; marginal 

 interspace with two punctures just back of the strong sigmoidal dislocation of 

 the eighth stria, and three more at the anal curve. In a second male the entire 

 head and upi)er siu'face are yellow with all spots very small and faint, pale 

 bro^vn in color; legs as in mobilw. In the female the markings are fuscous 

 throughout , those of the head, prothorax, and inner row of elytral spots broadly 

 suffused, the head antl thorax ))redominantly fuscous, the elytra with the dark 

 areas a little in excess; tibiae blackish excci)t at base, femoral rings broad, 

 leaving the base and apex pale. 



Length 2.4 to 3.4 mm.; width l.o.") to 1.7.") mm. 



Distribution. — Texas: Davis ^Mountains, July 6 (II. -V. ^\'(■nzel). 



TRANS. AM. ENT. SOC, XLI. 



