REVISION OF ELF.ODIINI BLAISDELL. 489 



Vdlvula. — Dorsal plate triangulo-oblong and not at all defined 

 from the apex, external margin moderately convergent apically ; 

 surface more or less concave and with scattered punctures externally 

 and aj^ically, each puncture with a moderately short seta ; external 

 margin straight to feebly and broadly sinuate, continuous with the 

 subacute margin of the apex, the latter slightly emarginate exter- 

 nally for the minute fossa; internal margin quite straight; apical 

 margin not in the least evident, apex not at all defined from the rest 

 of the valve, obliquely conforming to the plane of the dorsal plate, 

 more or less rounded at tip, which is subacute and finely setose within. 



Afpendage minute and punctiform, apparently slightly com- 

 pressed, calvous. 



Superior pudendal memhrane long, attaining the base of the apex, 

 finely longitudinally rugulose, narrowly exposed. 



Banal prominences not evident. 



Ventrolateral surfaees not longitudinally convex, moderately so 

 laterally; surface very glabrous and not defined from apex; sub- 

 marginal groove very feebly defined for a short distance cephalad 

 to the appendage; apex with fcAv scattered setae. Internal margins 

 of the valves contiguous in basal moiety, fissure nari'ow in ajiical 

 half, membrane not visible. 



Ilahitat. — Western Nevada and the contiguous eastern California ; 

 Idaho (Eock Creek). 



Number of specimens studied, ?>. 



Type in the LeConte collection. 



Type-loealify. — Rock Creek, Owyhee County, Idaho. 



Salient type-characters. — Elongate, dirty black, opaque. Head and 

 thorax coarsely and confluently cril)rate, the latter with two deep 

 oval fovea^ occupying nearly the whole of the median line. Elytra 

 elongate oval, with suture and four discoidal costa^ acutely elevated, 

 intermediate furrows deeja and broad, subreticulate (LeConte). 



Diagnostic characters. — The distinctly cribrately punctate prono- 

 tum distinguishes costatus from tvhercidatiis ; in the latter species 

 the elytral costa; are asperate and not smooth as in the former. 



The mentum is somcAvhat small and more or less trapezoido-trian- 

 gular, foveate laterally, not noticeably strongly sculptured. 



The prosterinun is strongly protuberant ventrally before the coxa?, 

 arcuately declivous anteriorly and quite horizontal between the 

 acetabula, feebly longitudinally grooved at middle from anterior 

 margin; surface asperately punctate and sparsely setose, setse short; 

 produced and acute posteriorly. 



Mesosternum deeply and l)roadly concave, sides prominent. 



Metasternum laterally between the coxae as long as the width of a 

 mesotibia nt middle. 



