84 COLEOPTERA OF NORTH AMERICA. 



The genus Psilopyga is remarkable for its close resemblance, in 

 appearance, to Hister. 



Tribe IV.— CYCHRAMINI. 



The species of this tribe are rounded or oval, convex insects, 

 living in fungi. One geuus (Cybocephalus Er.), not yet found 

 with us, has the power of contracting into a ball, like Agathidium 

 and Clambus, from which it will be distinguished by the anterior 

 coxae not being prominent. 



I. All the tarsi equal in length ; 



Tarsi all dilated ; presternum scarcely produced. Cychramus. 



Hind tarsi not dilated. Amphiceossus. 



II. Hind tarsi elongated ; presternum but slightly produced. Pallodes. 



Tribe V— IPINI. 



The species of this tribe are oblong, sometimes elongate species, 

 usually prettily variegated with red spots on the elytra. They are 

 readily known by the epistoma being prolonged between the man- 

 dibles; the elytra of Cryptarcha are rounded, of Ips and Pityo- 

 phagus are truncate. The species live upon fungi and under bark. 



Prosternal prolongation reaching the metasternum ; first joint of antennae 



covered by the front ; body oval, pubescent. Cryptarcha. 



Prosternal prolongation not reaching the metasternum ; body glabrous ; 

 Head immersed in the thorax to the eyes ; no sixth abdominal segment 



in the males ; body oblong, rarely elongate. Ips. 



Head not immersed as far as the eyes ; males with a sixth- abdominal seg- 

 ment ; body elongate, subcylindrical. Pityophagus. 



The species of the last genus entirely resemble in form those of 

 the next tribe, but are distinguished by the antennal club, com- 

 posed of three joints. 



Tribe VI.— RHIZOPHAGIffl. 



Small cylindrical or slightly flattened species, having the club 

 of the antennae solid and composed of the tenth joint, the eleventh 

 being closely connate with it; the labrum, as in the preceding 

 tribe, is concealed by the prolonged epistoma ; the elytra are trun- 

 cate, leaving the pygidium exposed; the anterior coxal cavities 

 are entirely closed, while in most of the genera of the preceding 

 tribes they are open behind; the posterior tarsi are 4-jointed in 



