NORTH AMERICAN COLEOPTERA. 55 



usually pubescent, and generally have a foveato puncture or impressed 

 line at the middle of base, rarely reaching to the apex, and not attaining 

 one-half that distance ; by the aid of the figures and the table the fol- 

 lowing groups may be recognized, the name of a typical species being 

 used to designate the groups : 



Body obese, elytra almost as broad as long Group veiitricosum. 



Body more elongate, very convex; elytra narrow at base, dilated to beliiml 



middle; pear-shaped Group pyrirorilie. 



Body more equal, Jiioderately convex; elytra more regularly ovate. 



Group crassinaNiim. 

 Body robust, sub-def)ressed above ; sides of elytra parallel ; thorax not cvlindric. 



Group seguipes. 



Body subcylindric ; thorax cylindric; sides usually arquate, and very slightly 



constricted at base; elytra elongate; sides subequal Group troglodytes. 



Group ventricosum, Plate .3, Fig. 9. 



This group contains but few species, very robust in form, which are 

 as follows : 



Thorax very short, sides equal ; elytra nearly as broad as long, 1.5 — 2 mm. 



ventricosam. 



Thorax moderate in length, sides somewhat arquate, elytra less broad, color 

 bronze-brown, eyes prominent, head broad, 1 mm Sllbglobosuui. 



Color black, slightly aeneous, head narrower, eyes less prominent, imt evidently 

 pul)eseent, 1.5 inn'i turbulentum. 



Opaque, distinctly pubescent, 1 mm iiliuor. 



A. ventricojiiiini Lee Pr. Ac. N. So. Phila., 1858. 78. — Black form, very 

 obese. Head elongate, distinctly punctured ; eyes not prominent, rostrum dis- 

 tinctly dilated near base. Thora.x densely punctured; sides equal, very little 

 wider at base; a short longitudinal dorsal fovea. Elytra very broadly ovate; 

 humeri prominent, striae fine, punctures distinct, intervals wide and flat. Beneath, 

 densely punctured. Length 1.5 — 2 mm. 



Hal). — Cal., Ariz.. Texas, Mass. 



Distinguished from the others in this group by the very short thorax 

 and the ventricose elytra. All the species in the group have the elytra 

 very broad, but none so broad as this, and in none of them is the thorax 

 so disproportionately short and narrow. 



A. suhglobosum Oerst. Stet. Ent. Zeit., 1854, p. 243.- Brassy, or bronze- 

 black, Ici^s piceous. sparsely pubescent. Head transverse, longitudinally rugose, 

 eyes prominent, antennae elongate, slender, second joint nearly equalling first in 

 all particulars. Thorax cylindrical, sides sub-equal, slightly widening to base, 

 moderately punctured, longitudinal impressed line from base to middle only. 

 Elytra widest behind the mid<lle, striae narrow, punctures small and rather close, 

 interspaces wide, flat, and smooth. Beneath finely scabrous and punctate. Length 

 1 mm. 



JIdli. — Florida. 



