IIELOrilOKIDES. 135 



J5. Maxillary palpi as long as head and thorax. 



Antennae nine-jointed ; last joint of maxillary palpi 

 longer and thicker than the penultimate joint ; labrum 

 strongly and narrowly emarginate ; eyes not very promi- 

 nent ; prosteruum ridged between the anterior coxae ; 

 abdominal segments not raised transversely. 



Hydraena, Kug. 



Helopliorus. 



A, Elytra with a short row of punctures at base between 

 first and second striae. 



ci» Alternate interstices on elytra raised into strong 

 ridges. 



I, Eidges on thorax interrupted. 



Oblong-ovate. Brown, usually covered with a dull 

 yellowish-brown crust ; elytra with dark spots ; antennae, 

 palpi and legs yellowish-red. Sides of thorax nearly 

 straight, longitudinal ridges very feeble, interrupted; elytra 

 with suture and alternate interstices strongly ridged, 

 sutural ridge ceasing near base, where there is a short 

 ridge between suture and short row of punctures. L. 1^ — 

 2 1. Common. H. rugosus, 01. 



II. Eidges on thorax not interrupted. 



1, Thorax not iridescent, length Ih lines. 



Oblong-ovate, dull. Gray-yellow ; thorax with five 

 furrows, sides scarcely dilated ; elytra rather lighter 

 coloured, with more or less distinct dark spots, with 

 notched furrows, interstices alternately raised and with 

 numerous small black spots. Common. IT. nuhilus, Fab. 



2, Thorax slightly iridescent ; length 2 lines. 



Oblong-ovate, somewiiat shiny. Brown, thorax slightly 

 iridescent ; elytra with a more or less distinct triangular 

 dark spot behind middle, and round pale spot before apex. 

 AEied to R. nuhilus, but usually larger, narrower, the 

 raised longitudinal ridges on the thorax more prominent ; 

 elytra with interstices less raised and pubescent. Eatlier 

 common. H. intermedius, Muls. 



I). Alternate interstices on elytra scarcely raised into 

 ridues. 



