TETRAMEROUS PLANT-BEETLES. 
163 
which I have found of much use in preparing the following tables of 
genera. Mr. Crotch unites all the Phytopliaga in the family of Chry- 
somelidm, which he divides into ten sub-families, as follows : Donaciides, 
Orsodacnides, Criocerides, Melolouthides, Cryptocephalides, Chrysome- 
lides, Eumolpides, Galerucides, Hispides and Cassidides. 
The Orsodacnides do not seem to us to be sufficiently distinct from 
the Criocerides, nor the Melolonthides (questionably so called) from the 
Crytocephalides, nor the Eumolpides from the Chrysomelides, to be re- 
tained as of equal rank. We will therefore divide the Chrysomelidce 
into the seven following sub-families. The accompanying tables of the 
minor groups exhibit a pretty full synopsis of N. American genera, ex- 
cepting a few which are composed of but one or two rare species, usually 
from the remote West: 
A. Body elongated; thorax not margined at the sides; head slightly constricted be- 
hind the eyes; eyes prominent; thighs usually more or less thickened. 
B. Body much elongated; first ventral segment very long; larvae live in the stems 
of plants Donaciides. 
B B, Body moderately elongated ; first ventral segment not much longer than the 
others ; larvm live on the leaves of plants, sometimes cover themselves with 
excrement Criocerides 
A A. Body more or less rounded (except Hispides) ; thorax almost always margined ; 
head not constricted ; eyes not prominent; thighs not swollen (except in 
Haltica and its sub-genera.) 
C. Antenna? distant, being wider apart at base than the length of the first joint. 
D. Body oval ; abdomen wholly covered by elytra ; larva? live exposed on 
l caves Chrysomelides. 
D D. Body usually short and sub-cylindrical; tip of abdomen vertical and 
uncovered; larvae live on leaves, in portable cases. Cryptocephalides. 
C C. Antennae approximate, being rarely wider apart than the length of the first 
joint. 
E. Antennae filiform and at least half as long as the body ; hind thighs, in 
one division, enlarged for jumping ; larvae live on leaves or between 
their laminae Galerucides. 
E E. Antenna; less than half as long as the body, and more or less thickened 
towards the tip. 
F. Head exposed; form oblong and usually sub-quadrate ; surface usually 
strongly pitted or reticulated; larvae live between the lam in® of 
leaves Hispide^. 
F F. Head concealed under the thorax; form hemispherical; surface 
usually smooth ; larvae live on leaves, covered by excrement : 
Cassidides. 
Sub family DONACIIDES. 
This sub family, composed mostly of the genus Donacia , Fab., forms 
a connecting link between the Lepturides of the preceding family and 
the Criocerides of the present. Their form is considerably elongated, 
and they can be distinguished with certainty by the unusual prolouga- 
