BYRRHIDAE. Ill 



Sub-Family II.— BYRRHIDAE (genuini). 



In this sub-family the head is retracted; the mentum small, 

 quadrate ; the base of the maxilla; largely exposed ; the labrum 

 distinct ; the antennae inserted under the sides of the head. 



I would arrange these genera in three tribes : — 



Epistoma short, coriaceous ; antennae 11-jointed. Amphicyktini. 



Epistoma not distinct ; antennae clavate, 11-jointed. Byrrhini. 



Epistoma corneous, separated by a fine suture ; antennae 10-jointed. 



Limnichini. 



Tribe I.— AMPHICYRTINI. 



These are distinguished by the front being finely margined, and 

 broadly rounded anteriorly, leaving a short coriaceous epistoma, 

 which serves as the base of the labrum. The labrum and mandi- 

 bles are never concealed. The legs are scarcely contractile, and 

 the antenna? are half the length of the body in Amphicyrta, a 

 genus confined to the Pacific maritime slope. They are found 

 under stones, and are very convex, ovate, smooth, black bronzed 

 insects, very different in appearance from the other members of 

 the family. 



Antennae nearly filiform ; third tarsal joint lobed. Amphicyrta. 



Antennae gradually but strongly clavate ; 

 Tarsi not retractile. Simplocaria, 



Anterior tarsi retractile (third joint of tarsi usually lobed). 



Pedilophorus. 



The tarsi of Amphicyrta are stated by Erichson to be not 

 retractile ; the posterior ones are in effect not retractile in A. 

 ehrysomelina, but very distinctly so in A. dentipes. Erichson has 

 substituted the name Morychus for Pedilophorus, on the ground 

 that the latter is not applicable to some of the species. 



Simplocaria tesselata Lee. is found at Lake Superior ; all the 

 other species of the tribe belong to the Pacific slope. 



Tribe II.— I1YKRIIIXI (genuini). 



Oval or rounded, very convex, dull black or bronzed insects, 

 Covered with a fine, easily removed pubescence, forming varied 

 patterns. 



The head is strongly retracted, and the antennae are always 



