108 GEO. H. HORN, M. D. 



In both sexes the last ventral segment has near the margin a feebly 

 elevated serrate ridge. The species has the appearance of a gigantic 

 sexsignata. This species, Merkelli and geymnata, form a very natural 

 group with the costse well defined ; they differ in the number, posi- 

 tion and distinctness of the fovea?. 



Occurs iu Texas, Arizona and Mexico. 



39. C. liboiioti n. sp. — Form moderately elongate, gradually attenuate 

 posteriorly, piceous slightly bronzed, beneath cupreous ; antennae more slender 

 to tip, third joint as long as the next two, geneous % , piceous 9 ; front rather 

 flat in male, not densely punctured, subopaque, seneous and without distinct cal- 

 losities, more convex and shining, nioi'e coarsely punctured, bronzed, and with 

 two feeble chevrons 9 ; clypeus (184) broadly triangularly emarginate at middle, 

 arcuate each side ; thorax nearly twice as wide as long, widest slightly behind 

 the apical angles, sides abruptly wider in front, then straight and oblique to 

 base; disc moderately convex, a deep median sulcus limited each side by an ob- 

 tusely elevated carina, a distinct oblique callosity in front and a depression ex- 

 terior to it ; surface finely punctured in the sulcus, very coarsely and confluently 

 otherwise ; elytra wider than the thorax, the humeri rather prominent, sides par- 

 allel in front, narrowed at apical third, the margins serrate, the apices acuminate ; 

 disc moderately convex, with the usual costse, the first distinctly elevated from 

 the apex to the middle, the others interrupted and dilated in smooth spaces more 

 or less confluent, the surface otherwise densely punctured, the basal fovea mod- 

 erately deep, the humeral impression distinct; body beneath feneo-cupreous, 

 shining, sparsely and finely punctate, the ventral segments without lateral cal- 

 losities, the margin of the last ventral segment not serrate, but with a slight in- 

 terruption one-third from the apex ; prosternum truncate in front ; anterior 

 femur with a moderately large tooth, obsoletely serrulate on its distal edge. 

 Length .32 -.48 inch; 8-12 mm. (Fig. 183.) 



iH«?e.— Prosternum nearly smooth at middle, a very few punctures, more 

 densely punctured iu front and at its angles ; anterior tibia (187) slightly arcuate, 

 without apical dilatation ; middle and posterior tibia; straight ; last ventral seg- 

 ment (185) deeply semi-circularly emarginate; last dorsal coarsely punctured, 

 subtruncate at apex. 



Female. —Prosternum and tibia^ as in the male ; last ventral (186) larger than 

 in the male, the apex tridentate. 



This species is peculiar among those with the elytra acuminate in 

 having the disc of the thorax deeply grooved at n:iddle. It is also 

 remarkable in having practically no difference between the sexes in 

 the prosternum and in the form of the tibiae. 



Collected in Arizona by Morrison. 



Grou]) VII. 

 The species of this group are all of small size, excepting impressa 

 and chalcophoroldes, and have in great part a feeble development of 

 elytral sculpture. They agree in having the last ventral segment 

 with entire margin and the apices of the elyti'a obtuse. 



