On Aquatic Carnivorous Coleoptera or Dytiscidce. 



317 



I. l^.— Genus NEPTOSTERNUS. 



Prosternal process tridentate ; spurs of hind tibiie acuminate at apex. Head 

 rather short ; hind angles of prothorax very acute. 



The unique species inhabits ^Madagascar and East Africa. 



175. Neptosternus ornatus, n. sp. — Oblongo-ovaUs, sat latus, subdepressus, 

 nitidus, laevigatus, rufus, elytris fuscis, maculis decern rufis ; prothorace angulis 

 posterioribus retrorsum spectantibus, per-acutis. Long. 3i, lat. 2 m.m. 



The peculiar hind angles of the thorax of this species will prevent its being 

 confounded with any other known to me. I have examined about twelve indi- 

 viduals, in all of which the Iront tarsi are slender, and I do not see any sexual 

 distinction. 



Madagascar : Zanzibar. 594. 



IV. 2.— Series Dytisci Complicati. 



Dytiscidse having the metathoracic episternum extending so far towards the 

 middle of the body as to reach the middle coxal cavity ; internal laminse of hind 

 «ox8e closely coadapted by a straight suture. 



The members of this extensive and complex series may be thus tabulated : — 



Hind coxffi separated from nietasterniim by a directly \ 

 transverse suture ; mentum reaching as far forward • 

 as front of the labrum. ) 



AMPUIZOA. 

 (Vide I). 318.) 



Ill all the following aggregates the hind coxae are separated from metasternum by a suture directed 

 foiwiu-cis as it piroceeds outwards, and the mentum does not extend so far forward as the labrum : — 



Presternum de- 

 flected between 

 the front coxse 

 so that the pro- 

 sternal process 

 is placed on a 

 quite dift'erent 

 plane of direc--l 

 tion from that 

 of the prester- 

 num ; this not 

 incrassate along 

 middle ; front 

 tarsi usually 4- 

 jointed. 



r Prosternal process 1 

 much deflected 

 from direction 

 of presternum. ')■ 

 Front tarsi 



usually with 

 only 4 joints. J 



Prosternal pi'oci 'ss^ 

 but little de- 

 flected from 

 plane of direc- 1 

 tion of pro- Y 

 sternum ; front 

 tarsi .5-jointed, i 

 scutellum not I 

 visible. J 



HYDROPORIDES. 

 {Vide -p. 319.) 



METULES. 

 { Vkle p. 489.) 



2 T 2 



