133 



near the base, the costse not cariniform but evidently an extreme 

 development of the obtuse ridges of the preceding group and some- 

 times taking that form in the present group; body rather small, 

 sometimes extremely slender in the male, always deep black through- 

 out Group III 



5 Pronotum coarsely and densely punctate, sometimes medially im- 

 pressed at base as in Group I, deplanate or concave and reflexed 

 at the sides; elytra with vestiges of three fine costules on each, the 

 outer of which joins the margin near the base; side margin obsoles- 

 cent, sometimes rather acute and distinct but not cariniform and 

 reflexed, except near the humeri; body very convex Group IV 



6 Elytra widest at or before the middle, more gradually acuminate 

 behind than in any other group, the prothorax rounded or angulate 

 at the sides; body always deep black throughout, very convex; 

 general form of the body strikingly imitative of Eleodes.. . .Group V 



Elytra widest well behind the middle, obovoidal, variably convex and 

 diversified in coloration, -7 



7 Sides of the very convex prothorax not explanate or reflexed but 

 having a fine cariniform margin; eyes larger than in any other group 

 and less transverse than elsewhere in the tribe so far as observed. 



Group VI 



Sides of the prothorax, which is always much less convex, concave and 

 reflexed, though more or less narrowly; body generally more or less 

 piceo-rufous, sometimes deep black Group VII 



These groups are not quite so strongly differentiated as those of 

 Pelecyphoms, but, at the same time, are to be considered subgeneric 

 in nature, as the fades is quite distinctive in each and a species can 

 be placed in its proper group without a moment's hesitation. 



Group I Type marginal us Lee. 



The species of this group are the largest of the genus and are 

 confined to the arid regions of Arizona and western New Mexico, 

 particularly to the southward, where they are numerous and 

 greatly diversified in form and sculpture. 



Elytra with small, sometimes very minute, sparse punctures, the pro- 



notal punctures generally very minute and sparse 2 



Elytra with coarse, much closer-set punctures, the pronotal punctures 



rather coarse and dense as a rule 1 1 



2 Marginal carina of the elytra short, never extending materially 



behind the middle 



Marginal carina long, extending at least to the convex apical declivity.. 6 

 3 Pronotum laterally rather abruptly deplanate but not at all reflexed 



and coarsely, closely, transversely rugose .4 



Pronotum similarly coarsely and closely rugose at the sides but sensibly 



reflexed 



4 Body blackish, alutaceous, the elytra dark rufo-piceous; head deeply, 



