164 
THE ORDER OF COLEOPTERA. 
tion of the first ventral segment, which is as long as all the others com- 
bined. They are between a quarter and half of an inch in length, and 
with a dark metallic lustre, of a greenish, bronze or purplish hue. The 
under side is paler, and clothed all over with an extremely fine silken 
prostrate pubescence, which enables them to shed the water, when the 
aquatic plants upon which they reside happen to be submerged, lhe 
species often closely resemble each other, rendering it difficult to draw 
the line between species and varieties. The larva; inhabit the stems of 
aquatic plants. When about to transform, they enclose themselves in 
silken cocoons, which are sometimes attached in rows upon the outside 
of the plants. 
Mr. Crotch enumerates twenty-five species as inhabiting the United 
States, two of which he describes as new, And refers the reader for a 
full description of the others to Dr. LeCoute’s Synopsis in the Proc. 
Acad. Nat. Sc., of Philadelphia, for the year 1852. 
Sub-family CRIOCERIDES. 
fFtg. 79 .] - This sub-family takes its name from the genus Crioceris , 
of Geoffroy, a word which literally means a ram's horn , but 
which is not especially appropriate to these insects, unless it 
I be by way of expressing their relationship to the preceding 
I family of Cerambycidte, in which the resemblance of the an- 
tenna; to the horns of the ram and the goat is much more 
striking. Like them, also, some of the beetles of the present 
0liT - sub-family have the faculty of making a squeaking noise, by 
the friction of one part of their bodies upon another. The Criocerides 
differ from the great majority of Chrysomelidm, in haviug the thorax 
almost cylindrical and without a lateral [I ' 80 ' 
niargin, and more decidedly narrower 
than the abdomen. The antennae are 
somew’hat moniliform, of the same 
width throughout, and about half as 
long as the body. The larvae live ex- 
posed on the leaves upon which they 
feed ; but some of them, of which the 
common Three-lined potato-beetle is an 
example, have the remarkable habit of lema tmlineata, oii v.:— « a, iarv® ; 
1 7 . od, eggs ; b, two last segments of tbe larva, 
protecting themselves by a covering OI showing the anal aperture on the upper side 
1 . i i xi of the last segment-after Riley. 
their own excrement, lo enable them 
to accomplish this purpose, the anal opening is upon the upper side of 
the last segment, and the excrement is pushed forwards upon the back 
by the pressure of that which is subsequently evacuated. The Crioce- 
rides of this country are contained in two leading genera : 
