388 ANNALS OF THE LYCEUM. 



much smaller, and the color is altogether different; the indenta- 

 tion of the head also is hardly perceptible. It is rather larger 

 than geminata nob., which, as I have ascertained, on close ex- 

 amination, has the elytra denticulated at tip. 



5. B. PUSILLA. — Blackish-green ; front without any obvious 

 impressed line. 



Desc. Body slender : head tinged with bluish, with obsolete 

 rather distant punctures ; excepting on the vertex, where they 

 are rather large and confluent ; frontal impressed line obsolete : 

 antennae black; thorax somewhat inequal; transversely confluently 

 punctured; two slight, dilated indentations placed longitudinally on 

 the disk, and a larger and more profound one on the lateral mar- 

 gin ; an elevated, arcuated line extends from the posterior angle, 

 almost to the middle of the lateral margin : elytra indented at 

 base, at tip rounded and minutely denticulated, the denticulations 

 not extending on the sutural or lateral edge. 



Length less than three-twentieths of an inch. 



This is so much smaller than either of the above species, as to 

 be distinguished readily by that character, without resorting to 

 any other. 1 detected it at the cantonment of Major Long's 

 party, on the Missouri. 



TRACHYS. 



1. T. OVATA. — Ovate, black; head without an indented line; 

 elytra without regular punctures. 



Desc. Body very short, ovate, black : head without the usua] 

 dilated indentation, but a very slight indentation may be observed 

 on close inspection, particularly on the [ 253 ] lower part of the 

 front ; slightly punctured : thorax equal, with the exception of 

 a dilated indentation on each side, with distant punctures in 

 which is a raised centre : scutel large, flat, impunctured, polished : 

 elytra with wide, irregular, not deeply impressed punctures, 

 without any appearance of a regular series ; no appearance of 

 elevated lines ; a profound excavation behind the humerus, with- 

 out any sinus of the edge ; humerus prominent. 



Length rather more than one-tenth of an inch. 



This is the smallest species I have met with, and of a shorter 

 form. 



[Afterwards, Trans. Amer. Phil. See, 6, 164, made the type 



