NORTH AMERICAN COLKOl'TICliA. 39 



densely placed, closer near the sides, less dense in the male than in the female. 

 Elytra a little wider than the thorax, sides parallel, humeri obtuse, moderately 

 deeply .striate, strife finely snbcrenately i)unctiired, intervals .slightly convex, 

 sparsely irregularly punctulate, the punctures more distinct in the females. Body 

 beneath sparsely punctate; mesosternum not carinate. Anterior tibiie. smooth 

 ill front, strongly tridentate externally, distinctly crenate above, the first tarsal 

 joint a little shorter than the second. Posterior femora sparsely jiunctate, the 

 first tarsal joint not as long as the next three. Length .18-.22 inch ; 4.5-^.5 mm. 



J/rt?e.— Anterior tibial spur not more slender to tip, obtuse at apex. Upper 

 -spur of middle tibise. truncate at tip, the inner angle slightly iirolouged inter- 

 nally. Thorax less closely punctured, elytral intervals less distinctly punctured. 



i^em«/e. —Anterior tibial spur slender and acute, upper spur of middle tibia 

 acute at tip. 



This species so closely resembles militarls that I had supposed them 

 identical until the examination of my material for the present paper 

 began. The males can be distinguished at first glance by the anterior 

 tibiae, but the hind angles of the thorax in the present species are 

 well marked, although obtuse, and in this manner either sex may be 

 distinguished from the preceding species. 



Occurs in southern Arizona (Morrison). 



A. rubiginosus Horn. — Moderately elongate, reddish brown, feebly shin- 

 ing. Aiitcnnte rufo-testaceous, club slightly darker. Head convex, front with 

 three very faint tubercles, densely punctate, punctures coarser near the sides, the 

 intervals distinctly alutaceons; clypeus broadly emarginate, subangulate each 

 side, sides arcuate, margin not fimbriate, gense feebly prominent, obtuse. Thorax 

 nearly twice as wide as long, not narrowed in front, sides feebly arcuate, margin 

 not explanate, hind angles well defined, nearly rectangular, the tip slightly ob- 

 tuse, base regularly arcnate with fine marginal line; disc convex, punctures 

 coarse, moderately close, larger, but not denser near tlie side, intervals aluta- 

 ceous. Elytra not wider at base than the thorax, humeri obtuse, sides feebly 

 arcuate, strise fine, moderately impres.sed, the punctures fine and rather close, 

 intervals feebly convex, moderately densely punctured, the punctures nearly as 

 large as those of the strife. Body beneath sparsely punctate. Mesosternum not 

 carinate. Anterior tibial smooth in front, strongly tridentate externally and 

 crenulate above, the first tarsal joint shorter than the second. Posterior femora 

 spar.sely punctate, the first tars.al joint a little shorter than the next three- 

 Length .22 inch ; 5.5 mm. 



3[(de. — Anterior tibial spur rather long, acute at tip and strongly arcuate ; upjier 

 spur of middle tibia acute at tip. 



The middle and posterior femora are slightly find)riate along their 

 posterior edge, and this is probably .sexual, but as I do not know the 

 female the characters of this sex cannot be given. The three ^)e- 

 cies— militarls, a'mulus and rubiginosn.^ — very naturally group to- 

 gether, are very closely related and resemble each other, so that 

 witlinut cai'cful examination thev mio'ht be conl'used. Tlie first two 



