160 
CHARLES W. LENG. 
fully SO, and the only form excluded is that in which the tip is evi- 
dently rounded. In such the sutural margin is sinuate. 
“ Mesosternum narrower than the coxa.” By this is meant that 
the portion of the under surface seen between the middle coxjb is 
narrower than those coxre separately. It is used as a convenient 
measure of the width of the insect, being narrowest in the conspicu- 
ously slender species, and may be inferred where it is difficult to see, 
as when the insect is pasted on a point. 
“ Sutural margin sinuate posteriorly.” In many Donacite the 
elytra are declivous at the apex ; the elytra are closely joined at the 
suture in repose, but the margins on the declivous portion appear 
double, and although they truly meet, there is a second apparent mar- 
gin within the true one. This second margin, starting not more than 
one-fourth the length from the tip — often less — is sinuate, or curved 
more or less, away from the suture. Thus a space somewhat ellip- 
tical in shape is formed, sometimes depressed, sometimes in the same 
plane with the rest of the elytron, and always destitute of punctua- 
tion. This sinuation might also be described as a sinuate displace- 
ment of the sutural stria. 
“ Posterior femora elliptical.” In all Donacise but ru/a, the j)os- 
terior femora are decidedly pedunculate. In that species the neck 
is not evident, and I have followed Dr. LeConte’s use of the term 
elliptical to describe them, though they are actually much broader 
at the apex. 
Certain characters are subject to great individual variation. These 
are the color, the relative length of the antennal joints, the number 
and size of the femoral teeth or spines, and the punctuation and 
sculpture of the upper surface. While diherences in these respects 
are, to an extent, indicative of specific rank, it is important that 
they be not carried too far, and I have endeavored to mark their 
limits in the descriptions which follow the synopsis. 
The dilation or extension into spinous ])rocesses of the tibiae is 
very evident in some species. In pis^eatrix and jKilmata this is esj)e- 
cially true of the middle tibiae, ami a spinule may also be seen beneath 
the dilation. In certain of the convex species the dilation is more 
apparent on the front tibiae. The character, however, varies greatly 
in individuals of the same species, and I have not made use of it in 
the synojLsis. 
The sexes in most Donaciae are widely differentiated. As a rule 
the females are broader, the posterior femora are either without or 
