" — ti.es. 100!) 



TIk'v have the head prominent, .^cmewhat narrowed behind the 

 eyes ; antenn;e filiform, slender, at lea.'^t half as long as body; thorax 

 quadrate ^-ithout side margins, not wider than head. Elytra wider 

 than thorax, dejiresseil. cylindrical or somewhat triangular, usually 

 narrowed toward the tii^s. and eacii marked with ten rows of quad- 

 rate, rarely roimded, punctiires. In color they are usually more 

 or less metallic, of a ureenish. bronze or purplish hue. The under 

 side is paler and densely cluthed with a fine silky pulieseence. which 

 enables them to shed the water when the plants upon which they 

 alight happen to be submerged. 



The principal papere treating of the tribe are as follows : 



LiContc. — "Syuonsis of the Spcii^s of Douacin Inhabiting the 

 United State.s." in Proc. Phil. Acad. Xat. Sei., V, ls.31. 

 310-316. 



Lciig, Chas. — "Ke^iew of the Donacia of Boreal America," in 

 Trans. Amer. Ent. Soc. XVIII, 1>9], l.j9-176. 



The tribe comprises but two genera, both of which are repre- 

 sented in Indiana. 



KEY TO GENERA OF DON-VCIIM. 



a. Elytra simple at tip; taisi dilated, spivisy beneath. I. Do.nalh. 



iia. Elytra distinctly spinose at tip; taisi narrow, smixjth beneath, last joint 



very long, claws large. II. II.Eiio>;iA. 



I. DoxACiA Fab. 177.5. (Or., "a reed.") 



Belonging tn this genus, as characterized above, Leng. in his 

 latest synojisis. recognized 2() spcs-ies and a niunber of varieties. 

 Eigliteen species have been taken in Indiana, while four others may 

 occur. 



In those species having the "sutural margin sinuate behind the 

 middle," there is an apparent second margin, starting not more 

 than one-fourth the length from the tip — often less — which is sinu- 

 ate, or curved more or less, away from the suture. Thus a space 

 somev.'hat elliptical in shape is formed, sometimes depressed, sume- 

 tinies in the same plane with the rest of the elytron, and always 

 destitute of punctuation. 



The males are narrower than the females and usually have the 

 hind femora more strongly toothed and the last dorsal segment 

 shorter and either truncate or emarginate, never rounded. Last 

 dorsal of female moie or less einntrate. always rounded. For con- 

 venience the Indiana sjieeies are separated into three groups and 

 these in turn into species. 



