516 1NSECTA. 



Monotoma, 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 little larger. The superior ex- 

 tremity of the club, or button, seems to present vestiges of 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 some, and smaller in others; all the joints 

 of the tarsi are entire. 



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

 of but two joints. They form the genus 



Lyctus. 



In some, the mandibles and first joint of the antennae are com- 

 pletely exposed. The body is narrow, elongated and almost linear: 

 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; the 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. 



