NORTH AMERICAN COLEOPTKRA. 34!^ 



wide, sides arcuate in front, thence oblique and straiglit to base, disc convex, a 

 slight impression at middle of base ; elytra obloiij; oval, humeri obtusely rounded', 

 the disc with seven nearly equally elevated costa*, the intervals with a single 

 series of coarse punctures, the summits of the costse with small, recumbent scales : 

 propleurse coarsely, sparsely punctate, somewhat rugose in front. Length 4 mm. ; 

 .16 inch. 



This species has a deceptive resemblance to regidaris in form and 

 color, but differs in the absence of the thoracic groove and the greater 

 number of elytral ridges. In this species and the next there is but 

 little difference between the costse in their elevation. 



Collected in southern Arizona by Moriison. 



A. arinatlis Horn, Trans. Amer. Philos. Soc. xiv, 1870, p. 275. 



The head is longer than wide, the sides straight and narrowed from 

 the base of the antennse, at base abruptly narrowed to the neck. 

 Thorax about as wide as long, sides arcuate in front, then obliquely 

 narrowed to base, disc convex, with a vague median sulcus. Elytra 

 oblong oval, humeri broadly rounded, disc with seven elevated lines, 

 the intervals with a single series of coarse punctures, the summits of 

 the ridges with short, semi-erect, scale-like hains. Propleura? coarsely, 

 rather closely punctate and rugose. Anterior and middle fetnora 

 toothed in front of middle. Length 3.5— l mm. ; .14-. 16 inch. 



Resembles the preceding in appearance, but easily known from all 

 the other species by the dentate femora. 



One specimen, Owen's Valley, Cal., Green River, Wyo., Wickham. 

 Mr. Wickham observed these associated with ants in the same man- 

 ner that I had noticed sulcicollis ; this is, however, merely an acci- 

 dent of habitat, as Arjeoschizus is neither parasitic nor inquiline. 



