98 INSECTA. 
Syncnita, Hellw., Dej.—Lycrus, Evornorus, Fab. 
Where the anterior extremity of the head is transverse and with- 
out any prolongation, where the two first joints of the antenne are 
almost identical, and where the thorax, much wider than it is long, is 
separated from the base of the elytra by an evident interval *. 
Certyon, Lat—Synenita, Hellw.—Lycrus, Fab. 
Where the anterior extremity of the head projects in the manner 
of an obtuse triangle; the first joint of the antenne is much larger 
than the second; the thorax is applied posteriorly to the base of the 
elytra, is wider than it is long, or almost isometrical, and without 
any recurvature of the margin. The body is almost oval or nearly 
forms a parallelopiped, and the elytra are truncated posteriorly and 
cover the whole top of the abdomen f. 
Ruyzornacus, Herbst., Gill—bLycrus, Fab. 
Resembling the preceding in the head, the relative dimensions of 
the first joints of the antenna, and the junction of the thorax with 
the abdomen; but the body is narrow and elongated, the thorax 
wider than long, with a recurved margin; the elytra are truncated 
posteriorly. Some authors have asserted, that by their tarsi they 
are heteromerous—TI rather think they prove them to be penta- 
merous f. 
The others, 
Monotoma, Herbst.—Cerryon, Gyll., 
Or Monotoma 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 antenne are stouter than the following 
ones, and almost equal—the first a little larger. The superior extre- 
mity of the club, or button, seems to present vestiges of one or two 
joints. The head is triangular, and somewhat extended into an ob- 
tuse snout. The body is elongated, and the thorax longer than it is 
wide §. 
3. The Xylophagi of the third division have eleven very distinct 
joints in the antenne; their palpi are filiform, or thicker at the extre- 
mity 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 antenne con- 
sists of but two joints. They form the genus 
Lyctus. 
In some, the mandibles and first joint of the antenne are com- 
* Cerylon terebrans, Lat.; C. juglandis, Gyll. 3 Lyctus juglandis, Fab.; Elophorus 
humeralis, Ejusd. 
+ Cerylon histeroides, Lat., Gyllenhall. 
t See Gyll., Insect. Suec., I, iii, p. 419. 
§ Cerylon picipes, Gyllenhall, 
