CHRYSOMEHDAE. 337 



Tribe I.— DOXAClI.\I. 



The species of this tribe are graceful and active species, usually 

 of metallic color, which live upon Nyniphaja and other water- 

 plants. They are usually gregarious, and may be seen in bright 

 sunshine, flying and alighting on the leaves, very much after the 

 manner of CicindelidsB. The under surface is clothed with fine 

 hydrofuge pubescence. 



The head is prominent, somewhat narrowed behind the eyes, 

 which are entire, convex and prominent, though not very large. 

 The mouth is advanced, forming a short stout muzzle, and tlie 

 antenntB are inserted upon the front, before the eyes, and are 

 not very distant at base ; they are nearly filiform, slendei', and 

 half as long as the body. The prothorax is quadrate, not wider 

 tiian tlie head; the side pieces are somewhat distinctly indicated, 

 but there is no lateral margin. The elytra are wider than the 

 prothorax, triangular, or cylindrical, with ten rows of quadrate 

 punctures, and a short scutellar one; epipknnie very narrow, 

 indistinct. Front coxae prominent, nearly approximated, cavities 

 closed behind, angulated externally. Middle coxie rounded, 

 separate ; hind coxa; widely distant, oval. Legs long, hind 

 thighs frequently clavate and toothed, spurs of front and hind 

 tibige sometimes distinct; claws simple. First ventral segment 

 as long as the others united. 



The genera are but two, both represented in our fauna: — 



Tarsi dilated, spongy beneath. Donacia. 



Tarsi narrow, glabrous, last joint very long, claws large. Hcemonia. 



Of the second geims, one species occurs in both regions, 

 suijuquatic, upon Potamogeton. 'JMie species of Donacia are 

 numerous, especially in the northern parts of the Atlantic region. 



Tribe IT.— SAGRIIVI. 



This tribe, represented in the tropics by large and splendidlv 

 colored species, consists in our fauna, of but a few degraded and 

 insignificant forms, of dull color. 



The head is [)rominent, not narrowed behind, eyes small, entire, 

 and convex; mouth forming a short muzzle; epistoma large, dis- 

 tinct. Antenna; filiform, or nearly so, situated on the front in 

 advance of the eyes, rather widely separated. Prothorax not 

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