516 INSECTA. 



MoNOTOMAj Herbst. — Cerylon, Gyll. 



Or Monotonia properly so called, have a head of the same width 

 as the thorax, and separated from it by a strangulation. 



The two first joints of the antennae are stouter than the following 

 ones, and almost equal — the first a little larger. The superior ei- 

 tremity of the club, or button, seems to present vestiges o.f one or 

 two joints. The head is triangular, and somewhat extended into an 

 obtuse snout. The body is elongated, and the thorax longer than 

 it is wide(l). 



3. The Xylophagi of the third division have eleven very dis- 

 tinct joints in the antennae ; their palpi are filiform, or thicker 

 at the extremity in sorme, and smaller in others; all the joints 

 of the tarsi are entire. 



We will begin with those in which the club of the antennae consists 

 of but two joints. They form the genus 



Lyctus. 



In some, the mandibles and first joint of the ai(|tenn3e are com- 

 pletely exposed. The body is narrow, elongated and' almost linearjj 

 the eyes are large and the thorax is elongated. 



Lyctus, Fab. (2) 



In Lyctus proper, the margin of the head covers the whole or 

 greater part of the first joint of the antennae. The mandibles are 

 not salient. In 



DiODESMA, Meg. Dej. 



The antennae are as long as the thorax, the body is a convex, ob- 

 long oval, the thorax is almost semiorbicular, and the abdomen 

 nearly oval(3). 



BiTOMA, Herbst. Gyll. — Lyctus, Fab. 



Where the antennae are shorter than the thorax; the body is long, 

 narrow, depressed, and almost a parallelopiped; thp thorax is 

 square(4). 



(1) Cerylon picipes, Gyllenhall. 



(2) See Lat„ and Gyllenhall. The genus Lyctus of Fabricius is a mixture 



(3) Diodesma subterranea, Dej., Catal., p. 67- 



(4) See Lat., Gyllenhall. 



