500 TRANSACTIONS OF THE 



marginal groove interrupted at the posterior angles by an oblique 

 carinated line, dorsal line obsolete, basal ones dilated, basal edge 

 oblique each side : elytra whitish-testaceous, striae punctured, 

 profound, not obsolete near the tip, interstitial lines hardly con- 

 vex, third with a transverse linear impression before and one 

 behind the middle, area of the scutel greenish, two fuscous, ob- 

 solete, [85] undulated bands behind the middle, the posterior 

 one less definite ; feet whitish-testaceous. 

 Found in Missouri by Mr. Nuttall. 



5. B. CONTRACTUM. — Bkckish-brown, thorax much contract- 

 ed behind, base hardly broader than the peduncle, rectilinear. 



Length one-fifth of an inch. 



Head black ; antenae brown, base rufous ; labrum deep piceous ; 

 mandibles piceous before the tip ; palpi piceous black ; thorax 

 black, slightly cupreous, widest rather before the middle, much 

 contracted behind, lateral groove not dilated, posterior angles 

 very small, base excepting the angles, hardly wider than the 

 peduncle, basal line rectilinear ; elytra blackish, or dark piceous, 

 slightly glossed with cupreous, with a very indistinct paler pos- 

 terior margin and tip, striae impressed, obsolete at tip, lateral 

 ones shortest, punctures very distinct, approximated, interstitial 

 lines flat, third with a puncture before and one behind the mid- 

 dle ; feet testaceous. 



The pale hind margin and tip are usually obsolete, and often 

 almost imperceptible; it varies in extending to the base, but is 

 ordinarily in the form of a very indistinct, subterminal, margi- 

 nal spot, and an apical larger one. 



6. B. NIGER. — Purple-black ; elytra bronzed, striae obtuse, 

 obsolete at tip ; feet rufous. 



Length more than three-twentieths of an inch. 



Tachys niger Melsh. Catal. 



Body beneath piceous-black ; head blackish tinted with purple ; 

 antennae fuscous ; base and palpi rufous ; thorax black, slightly 

 purpurescent, broadest rather before [86] the middle, lateral 

 edge slightly excurved near the posterior angles, basal edge 

 slightly oblique each side ; elytra dark bronzed, striae obtuse, 

 somewhat canaliculate, obsolete behind, punctures transverse, 

 interstitial lines convex ; feet rufous. 



[Vol. II. 



