THK PRKPAOEOTTS VtlVTXf! BEETLKS. 211 



hh. Lower spur of liiiul libi.-r (lihilcd. iimcli I. render lliau the other; front 

 tarsi of males as in Difti^sciiii; liind tarsi witli one claw (malos) or 

 very unequal claws (females) ; lenj^th ."SO or more nun. 



Tribe IV. Cyhistrtni. p. 2:ir>. 



Tribe I. HYDROPORINI. 



Species of small size liaving the third joint of the front and 

 middle tarsi deeply lobed and coneealiny the fonrth joint, which, 

 liowever, is often wanting; the fifth joint slondei, witli claws which 

 sometimes vary in form according to sex. 'I'lic "elytral lignla" 

 mentioned in the key is a tongue-like process on the inner face of 

 the side margin of the elytra, which must he lifted to show it. Its 

 function is to unite more perfectly the elytra and ventral segments. 

 Seven genera are probably represented in Tndiaiia. 



KEY TO GENERA 01'' UYDUOPORIN I. 



((. Hind coxal cavities widely separated, each witli an eloui^ate notch be- 

 hind. I^ • Hyijuovatus. 

 aa. Hind coxal cavities not notched behind. 



h. Size small. 1.5-2 mm.; first ventral segment liniily united to border 

 of hind coxfe. 



c. Form rounded, convex ; prosternal process rhoniboidal. acute at tip. 



V. Desmopachria. 

 cc. Form ohiong. de])ressed; prosternal process oblong. 



VI. BiDESSUS. 



hi). Size larger, 2.5 or more mm.; tirst ventral segment free. 



d. Scutellum visible. VII. Celina. 

 dd. Scutellum not visible. 



e. Elytral ligula distinct, abrupt. VIII. CcELAMrus. 



ee. Elytral ligula wanting. 



/. Mesosternum not reaching the metasternum. Deroxectes. 



/■/. Fork of mesosternum connected with the intercoxal process of 



the metasternum. IX. Hy-droporus. 



TV. Hydrovattts Mots. 1855. (Gr., ''water + old or stagnant.") 



This genus includes very small beetles which have the proster- 

 num dilated triangularly behind the front coxas and the tips of the 

 elytra produced into a sutural point. Two species are known from 

 Indiana. 



400 (1257). Hydrovatus pustulatus Melsh.. Pi'oc. Phil. Acad. Nat. Sci., 

 II. 18M, 29. 



Form rounded, convex. Head, thorax (except basal cross-blotch) and 

 under parts reddish-yellow; elytra dark roddish-brown with a broud i)ost- 

 basal and a narrow subapical cross-bar orange. Upper surface alutaceous ; 

 thorax faintly, elytra distinctly but sparsely, punctate. r>ength 2-2.5 mm. 



Northern two-thirds of State; frequent. May 1.5 -August 20, 



