258 COLEOPTERA OF NORTH AMERICA. 



Fam. lv.— gedemeridae. 



Mentum trapezoidal, slightly narrowed in front, supported 

 by a large gular process ; ligula large, prominent, bilobed ; 

 labial palpi 3-jointed. 



Maxillae with large exposed base, and two flattened ciliate 

 lobes ; palpi 4-jointed, last joint dilated in our genera. 



Head slightly inclined, gradually, but not strongly narrowed 

 behind, received into the thorax not as far as the eyes, which 

 are tolerably strongl} 7 granulated in Calopus, but more finely 

 in our other genera ; front somewhat prolonged ; epistoma 

 subcoriaceous ; labrum prominent ; mandibles emarginate at 

 tip, furnished on the inner margin with a membranous ciliated 

 border. 



Antenna? 11 -jointed, nearly filiform, sometimes serrate. 



Prothorax narrower at the base than the elytra, lateral 

 suture wanting; coxal cavities widely open behind, con- 

 fluent. 



Mesosternum pointed behind ; side pieces extending to the 

 coxal cavities, which are generally confluent ; metasternum 

 long ; side pieces narrow. 



Elytra covering the abdomen ; epipleurae almost wanting ; 

 visible only near the base. 



Abdomen with five free ventral segments, the 6th some- 

 times visible in the males. 



Legs moderate ; anterior coxa? large, conical, contiguous ; 

 middle coxa? conical, contiguous or slightly separated, some- 

 times with distinct trochantin ; hind coxa? transverse, nearly 

 contiguous ; tibial spurs distinct ; anterior and middle tarsi 

 5-jointed ; hind tarsi 4-jointed ; the penultimate joints dilated 

 in our genera, and furnished with a dense brush of hairs be- 

 neath ; claws simple, slightly dilated at the base. 



Insects of moderate size found generally upon plants, though 

 some species of Asclera live near water on the ground. 

 Our genera are as follows : — 



Antennae partly surrounded by the eyes ; middle coxae not contiguous ; 

 Clypeal suture not obvious. Cai.opus. 



Clypeal suture very distinct. Microtoncs. 



Antennae not surrounded by the eyes : middle coxae contiguous ; 



Anterior tarsi with more than the 4th joint spongy pubescent beneath ; 

 Anterior tibiae with two distinct spurs. Ditylus. 



Anterior tibiae with but one spur. Nacekdes. 



i 



