162 
CHARLES AV. LENG. 
Group B. 
The s]iecies comprised in this grou]) are similar in appearance, all 
being evidently flattened above ; the first ventral segment is not only 
flattened, but longer than all the others combined ; the color is 
frequently testaceous ; the middle tibite are expanded at tip and are 
armed beneath with a spinule ; the mesosternum is conspicuously 
broad in all excej)t piscatrix male. These are the species which 
frequent the pond lilies, and Mr. Blanchard has suggested that their 
great breadth of beam indicates an adaptation to their particularly 
aquatic existence, in which connection it is worthy of note that the 
])ubescence of the under surface, characteristic of the tribe, is in 
them especially develojied. The species are : 
Thorax narrowed in front; posterior femora plnridentate male, simple female. 
floridte. 
Thorax quadrate, or wider in front; posterior femora dentate in both sexes, the 
male often hi- or tridentate. 
Auteunffi with second and third joints nearly equal ciiicticoriiis. 
Auteuuffi with third joint much longer than second. 
Elytra truncate. 
Anterior tarsi of male dilated palinata. 
.Anterior tarsi simple liypoleiica. 
Elytra subtruucate, form more convex; first ventral segment of % exca- 
vated piscatri.x. 
The specimens which I include under the name cincUcornis may 
be divided into three species or varieties or races as follows: 
Prothorax not coarsely punctate. 
Posterior femora male very large and strongly dentate, posterior tibiae curved 
and serrate lucida. 
Posterior femora less developed unnamed. 
Prothorax punctate at base and apex only; posterior femora less developed. 
tibiae straight, or nearly so proxima. 
Prothorax coarsely punctate over its entire surface ; femora and tibiai as in pre- 
ceding magnifica. 
From the number of specimens before me, showing all gradations 
in the thoracic sculpture and femoral armature, I do not think these 
forms can be recognized as species, and I suggest that they be placed 
in our lists as varieties. 
Group C. 
'fhis group includes subtilis, of which the female might, with equal 
propriety, be placed in the preceding group, though the male is de- 
cidedly more convex ; and several species which, by their convex 
form, are associated with the last group, l)ut differ in the truncate 
