CIOIDAE. 209 



Our genera are two, both containing species of small size : — 



Anterior tibiae with the outer apical angle prolonged. Lyctds. 



Anterior tibiae with the outer apical angle not prolonged. Tkogoxylon. 



The type of Trogoxylon is Xylotrogus parallelipipedus Mels., 

 from the Middle States. 



Lyctus is attached by Lacordaire to the Cioidae, but he ad- 

 mits the difficulty of placing it properly in any family ; from the 

 5-jointed tarsi, with the first joint very short, and the distinct 

 terminal spur of the anterior tibia?, I think it and Endecatomus 

 are more naturally placed in the present than in the next family. 



Lacordaire states that the anterior and middle coxae are con- 

 tiguous in Lyctus ; they are not so in any of our species, and 

 although nearly in contact in L. striatus, they are widely separate 

 in L. planicollis. 



Fam. XLVI— CIOIDAE. 



Mentum trapezoidal, corneous ; ligula without paraglossae ; 

 palpi short, 3 -jointed. 



Maxillae exposed, at the base, with, two flattened, ciliated 

 lobes ; palpi short, 4-jointed. 



Antennas inserted at the anterior margin of the eyes ; 8 — 

 10-jointed, with the last three joints larger, forming a loose 

 club. 



Head more or less- protected by the thorax ; epistoma 

 usually with a reflexed margin ; labrum distinct ; mandibles 

 short in our genera ; clypeal suture distinct ; eyes rounded, 

 somewhat coarsely granulated. 



Prothorax with the lateral margin distinct; cylindrical, 

 rounded in front, and prolonged over the head ; occasionally 

 toothed or horned ; coxal cavities small, separate, narrowly 

 closed behind. 



Mesosternum short, triangular; side pieces scarcely ex- 

 tending to the coxae. 



Metasternum large ; side pieces narrow, linear. 



Elytra entirely covering the abdomen ; epipleurae narrow. 



Abdomen with five free ventral segments, the first longer 

 than the others. 



Anterior and middle coxae oval, not prominent, without 

 trochantins ; hind ones transverse, separated. 



Legs moderately short ; tibiae either dilated and serrate, 

 14 



