160 COLEOPTERA OF NORTH AMERICA. 



Tribe 1— AMPHIC¥KTIIVI. 



These are distinguishod by the front being finely margined, and 

 broadly rounded anteriorly, leaving a short eoriaceous epistonia, 

 which serves as the base ol' the labrum. The labruni iuul niaiidi- 

 IjIcs are nevta* coneealed. The legs are searetily contractile, and 

 the antenniE are half the length of the body in Aniphicyrta, a 

 genus, confined to the Pacific raai'itime slope. Tliey are found 

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

 insects, very different in appearance from the other members of 

 the family. 



Antennse 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 efiect not retractile in A. 

 chry some Una, but very distinctly so in A. clenlipes. Erichson has 

 substituted the name Morychus for Pedilophorus, on the ground 

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



One species of Simplocaria, and one of Pedilophorus are found 

 in New England and at Lake Superior; the other species are 

 from the Pacific slope. 



Tribe II.— BYRRIIIIVI (genuini). 



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

 covered with a fine, easily removed pubescence, forming varied 

 patterns. 



The Ijcad is strongly retracted, and the antennae arc always 

 clavate; the labrum is distinct, and fits closely to the front, leav- 

 ing no epistoma 



The species are found under stones; on the Pacific coast none 

 have occurred south of Oregon. 



Mandibles concealed by presternum in rei^ose, labrum visible ; 



Anterior tarsi retractile. Cytilus. 



All the tarsi retractile. Byrrhus. 



Mandibles, eyes, and labrum concealed in rej^ose. Syncalypta. 



The species of the last genus have on the upper surface long, 

 clavate, upright bristles. 



