128 PALHCORNIA — HYDROPHILIDAE. 



A a. Labial palpi long and slender ; maxil- 

 lary palpi long, second joint considerably 

 longer than third, and third than fourth, 

 fourth joint not quite half so long as 

 second. 



Oldong oval. Elytra with a furrow near suture. 



Philhydrus, Sol. 



li h. Labial palpi rather short ; maxillary 

 palpi rather long, second joint longer than 

 third and fourth, which are equal in 

 length. 



Oval. Elytra with a furrow near suture ; front of cly- 

 peus strongly emarginate ; sternal ridge strong. 



Enochrus, Th. 



2, Maxillary palpi short. 



A A, Posterior femora smooth and shining be- 

 neath. 

 Short oval, convex. Mesosternum ridged ; tibiae very 

 strongly spined ; second and fourth joints of maxillary 

 palpi about equal in length, third rather shorter ; labial 

 palpi short, third joint not quite so long as second ; front 

 of clypeus strongly emarginate ; sternal ridge strong. 



Faraci/mus, Th. 



li Ji. Posterior femora densely pubescent be- 

 neath. 



Convex, nearly hemispherical or oblong. Mesosternum 

 simple ; tibiae strongly sj)ined ; fourth joint of maxillary 

 palpi rather longer than either of the others ; labial palpi 

 very short, third joint stout, nearly as long as second ; 

 front of clypeus slightly emarginate ; sternal ridge feeble. 



Anacaena, Th. 



h. Antennae eight-jointed. 



I, Body short oval ; posterior tibiae not fringed. 



Elytra with numerous rows of punctures. Anterior 

 tarsi of male somewhat dilated. Laccohius, Er. 



II, Body long oval ; posterior tibiae fringed. 



Elytra with deep punctured striae. Second joint of male 

 anterior tarsi strongly dilated. Berosus, Leach. 



7>. Abdomen with sLx or seven visible ventral segments. 



