Donacia.] I-HTTOPHAGA. 209 



b*. Interstices of elytra at base not, or 

 scarcely, punctured ; average size 



smaller. 

 at- Form more elongate ; upper surface 



duller and less evidently impressed ; 



teeth of posterior femora sharp and 



distinct D. THALAMINA, Germ. 



bf. Form shorter ; upper surface more 



shining and more evidently im- 

 pressed ; teeth of posterior femora 



indistinct D. IMPBESSA, Payk. 



3. Posterior femora of male without teeth. 



A. Elytra sharply truncate or emarginate at 

 apex, with both the apical angles well 



marked. 



a. Elytra without reddish-purple stripe 

 near suture ; anterior angles of thorax 



more prominent D. SIMPLEX, /'. 



(linear in, Hoppe.) 



b. Elytra with a reddish-purple and blue 

 stripe near suture ; anterior angles of 



thorax less prominent D. TULOARIS, Zsch. 



(tyfhte, Ahr.) 



B. Elytra obtusely truncate or separately 

 rounded at apex, the exterior angles at 



least being rounded. 



a. Length 7-12 mm.; thorax transversely 

 wrinkled, shining, sometimes almost 



smooth D. CLAVIPES, F. 



(menyanthidis, F.) 



b. Length 6-9 mm. ; thorax closely and 



strongly punctured D. SEUTCCFKEA, Pan:. 



(simplex, F. (Syst. El.).} 



ii. Upper surface thickly pubescent ; posterior 

 femora without teeth, and not reaching apex of 



elytra D. CINBBBA, Herlst. 



(hydrochceridit, F.) 



II. Tibia? produced externally into a tooth at apex ; 

 mandibles stout, projecting considerably beyond 

 labrnm ; first segment of abdomen equal to, or 

 rather shorter than, the remainder taken 



together. (S.g. Plateumaris, Thorns.) 

 i. Elytra with impressions; legs metallic, xini- 

 colorous with body ; posterior femora with a 

 strong triangular tooth in both sexes. 



1. Antennas longer, with the third joint longer 

 in proportion ; anterior angles of thorax 

 acute and reflexed, and the callosity near 



these angles clearly defined D. SERICXA, L. 



2. Antennae shorter, with the third joint shorter 

 in proportion ; anterior angles of thorax 

 rounded and deflexed, and the callosity near 



these angles less distinctly defined . . . . D. DISCOLOR, Pant. 



(comari, Buff.) 



ii. Elytra without impressions ; legs red ; posterior 

 femora with a strong tooth in male and a 

 frrble tooth in fcin:tlf. 



