12 COLEOPTERA OF NORTH AMERICA. 



Sub-Family II.— PIESTIDAE. 



Insects having a slender and frequently very depressed form, 

 living under bark. The prothoracic spiracles are covered, and 

 the whole prosternum is corneous, and in some genera separates 

 the anterior coxae so that the coxal cavities become entire. The 

 antennae are situated under the sides of the front, straight, slightly 

 thickened externally. The second ventral segment is longitudi- 

 nally elevated at the middle. 



In this sub-family the present family shows its strongest tend- 

 ency towards the collective Clavicorn families in Cucujidae ; in 

 the next we will find this tendency towards another member of 

 the same series. Our genera are as follows : — 



A. Anterior coxae contigucras ; 



Abdomen margined, tarsi 5-jointed ; 



Anterior tibiae spinous, abdomen broadly margined ; 

 Maxilloe with the outer lobe dilated; (elytra striate). 



Pkognatha. 

 Maxillae with the outer lobe not dilated ; (elytra punctate). 



Hypotelus. 

 Anterior tibiae not spinous, abdomen narrowly margined. 



Isomalus. 

 Abdomen not margined, tarsi 3-jointed ; (thorax and elytra costate). 



Glyptoma. 



B. Anterior coxae separated, abdomen not margined, tarsi 5-jointed. 



Lispinus. 



Sub-Family III.— MICROPEPLIDAE. 



This sub-family consists of a single genus, containing small 

 subquadrate species, having the thorax, elytra, and abdomen or- 

 namented with acutely elevated ribs; the antennas are inserted 

 under the sides of the front, 9-jointed, and terminate in a small 

 club received into cavities on the under surface of the prothorax ; 

 the prosternum is entirely corneous. The anterior coxae are 

 transverse, not prominent, the hind ones distant, rounded ; the 

 tarsi are 3-jointed. The second ventral segment is broadly di- 

 lated at the middle, and separates the hind coxae. 



This sub-family thus completes the approach of the Staphyli- 

 nidaa towards the Clavicorn series in Histeridoe. 



