DIAGNOSIS OF THE GENUS CALOPTENUS. 41 



reaching to or nearly to the clypeus. Pronotom sabquadrate, that is to say, a cross 

 section (in the middle) will present a quadrate figure or parallelogram with the upper 

 corners slightly rounded ; the sides are nearly perpendicular ; the disk or dorsal sur- 

 face is very nearly flat, with a little thread-like, median carina, usually distinct on tho 

 posterior lobe, but sometimes obliterated on the middle and anterior lobes ; the lateral 

 carinae are obtuse, but distinctly marked as the angle where tha disk and sides meet; 

 on the posterior lobe they sometimes appear as true carina3, though not prominent or 

 sharp; the lower margin of the sides is nearly straight, sometimes projecting a little 

 in the middle, where the triangular corner piece connects ; the posterior lateral margin 

 varies somewhat; in some species it forms a distinct entering angle at the shoulder or 

 lateral carina, in others it continues to the tip in an almost straight line; the three 

 transverse incisions ara distinct and situated close together, the posterior one being Oi 

 little behind the middle and always cutting the middle carina ; all three sever the 

 lateral cariuse, but the anterior one ends at the upper margin of the sides with a slight 

 and short curve forward ; the posterior and middle ones extend down the sides well 

 toward the lower margin, and most generally about midway down the posterior sends 

 out at right angles a branch sulcus which often crosses the intermediate space to the 

 middle one; there is also a fourth sulcus extending down the sides close to the 

 anterior margin ; the posterior sulcus and usually the middle one make a short curve 

 forward immediately at the median carina; the posterior margin is obtuse-angled, 

 rounded at the tip; the posterior lobe is usually finely punctured, while the middle 

 and anterior lobes have a velvety or felfcy appearance. 



The elytra and wings extend to or beyond the tip of the abdomen ; the former are 

 narrow (except in C. Mvittatus) ; the latter transparent in all our species ; sometimes a 

 very slight greenish-yellow or a bluish tinge is observed, the nerves usually more or 

 less dark. The abdomen is usually subcylindrical, presenting no distinct keel above ; 

 that of the male enlarged at the tip and curved upward ; the cerci are usually flat, 

 rounded at the tip, and curved up but some are straight and others tapering. The 

 last abdominal segment, which curves upward like the prow of a boat, is some- 

 times truncate above, sometimes with a slight angular notch. Posterior femora ro- 

 bust, much enlarged near the base, the external face more or less convex, in the 

 female never longer and generally shorter than the abdomen ; in the male the reveres 

 is the rule. Pads between the claws large, reaching a maximum size in some of the 

 species. Most of our species have the upper portion of the inner face of the posterior 

 thighs marked with three oblique dark bands (the one at the base often indistinct). 

 There is generally a dark stripe on the side running back from the eye to the 

 last transverse sulcus of the pronotum ; it is often interrupted, broken, or partially 

 obliterated, but is seldom wholly wanting in those species any way closely allied to C. 

 spretus or C. femur-ruhrum. The antennae are filiform and slender, reaching their maxi- 

 mum length in the male of C. differentialis, where they sometimes attain the middle of 

 the body. The prosternal spine is usually stout and conical, quadrangular at the base, 

 a,nd generally slightly transverse ; in one or two species it approximates the mesoster- 

 num, but this is not usual. 



Our species vary in length from 6-10 to 2i inches. 



The genus as thus characterized is represented in the territory em- 

 braced in our observations by a number of species, several of which 

 are so closely allied to C. spretus that it is difficult for any but an expe- 

 rienced entomologist to determine to which a specimen belongs. We 

 think it more than likely that future investigations will show that several 

 of the species which have been described as distinct are but varieties 

 of other closely-allied species. 



The following list contains all the species found in the United States 



