SCYDM^NIDAE. 83 



This tribe consists of very minute species, living in decompoH- 

 ing vegetable matter. 



The genera may be thus separated. 



Klytra margined at the sides with distinct epipleurse. Coxal plates narrow. 

 Antennae 11-jointed, club 3-jointed; moderately distant from the (iycs 

 ■ at base. 



Abdomen with seven segments. Empelus. 



Elytra not margined at the sides, withont epiplenrse. Coxal plates wide. 



Antennae 10-jointed, club 2-jointed ; arising at a distance from the eyes. 



Abdomen with six segments. Calyptomerus. 



Antennse 9-jointed, club 2-jointed; arising close to the eyes. 



Abdomen with five segments visible. Clambus. 



Empelus and Cali/pfomeruH have the elytra slightly pro- 

 longed and ol)liquely truncate, in ClambuH rounded at tip not 

 prolonged. 



The first two genera occur in Alaskd, the second extending 

 also to Lake Superior; Clambus occurs in the Atlantic region and 

 Arizona. The edge of the wings in this tribe is fringed with 

 long hairs, thus showing, a relationship, as already observed by 

 Motschulsky, with Trichopterygidffi and Corylophidae. 



Fam. XL— SCYDM^NIDAE. 



Mentum transverse, trapezoidal; ligula small, corneous, 

 e margin ate. 



Maxilla3 with two ciliate unarmed lobes; palpi long, witli 

 the last joint very small. 



Antennee inserted upon the front, at the inner margin of 

 the eyes (except in Brathinus and Chevrolatia), gradually 

 thickened or slightly clavate. 



Eyes composed of large lenses. 



Prothorax with the side pieces not distinct; prostcrnum 

 not visible between the coxjc. 



Mesosternum elongate, triangular, more or less carinate, 

 side pieces reaching the coxae. 



Motasternum large, side pieces narrow, cpimera distinct. 



Klytra convex, covering the abdomen; wings sometimes 

 wanting. 



Abdomen with six free ventral segments. 



Anterior coxae conical, prominent, contiguous ; middle 

 coxae Gonical, slightly prominent somewhat distant ; poste- 



