THE GROUND BEETLES. 



89 



a well-marked internal fold; disk usually with dorsal punctures. 

 Front tibiae broader at tip. deeply emarginate within, the inner spur 

 situated at the summit of the notch; hind coxse contiguous. Front 

 tarsi of males rather broadly dilated and covered beneath with small 

 scales. 



The tribe is represented in the United States by five genera, all 

 of which occur in Indiana. 



KEY TO GENERA OF PTEBOSTICHINI. 



a. Terminal joint of palpi dilated ; elytra without dorsal punctures. 



XXIII. Myas. 



aa. Terminal joint of palpi cylindrical or slightly oval. 

 &. Front tarsi of male normally dilated. 



c. Last joint of palpi as long as or longer than the next to the last, 

 the latter with two setae (bristly hairs) in front. 



XXIV. Pterostichus. 



cc. Last joint of palpi shorter than the next to last, the latter with 

 a number of seta? in front. 

 d. Elytra with one dorsal puncture ; size larger. 14 or more mm. 



XXV. Evaethbus. 



del. Elytra without dorsal punctures ; size smaller, not over 12 mm. 



XXYI. Amaba. 



t>T). Front tarsi ot male oblicpiely dilated; form oblong, subdepressed ; 

 black, very shining, usually with iridescent reflections; dorsal 

 punctures one. XXVII. Loxaxdrvs. 



- 



XXIII. Myas Dej.. 1828. 



Beetles of medium size and broad form, having the head and 

 thorax black and elytra purplish. Two species occur in the United 

 States. Of these but one has as yet been taken in Indiana, though 

 Dury has taken the other at Cincinnati. Ohio. They may be sepa- 

 rated as follows : 



KEY TO SPECIES OF MYAS. 



a. Thorax depressed at sides; elytra] striae punctured; length 1S-20 mm. 



120. coracixis. 



aa. Thorax not depressed at sides ; elytral stria? not or very obsoletely 

 punctured; length 13-15 mm. cyaxescexs. 



120 (494). Myas coracixus Say. Trans, liner. Phil. Soc. II. 1823, 59: 

 ibid. II. 4S2. 



Black, elytra purplish. Thorax broad, transversely quadrate, front 

 angles rounded, hind angles rectangular, margin purplish. Elytra broad 

 with acute stria? which are finely punctured. Length 1S-20 mm. 



Tnroughoivt the State but scarce : taken in nine widely separated 

 counties. Occurs beneath logs and chunks in open woods with a 

 loose soil. May 21-October 7. 



