36iJ On Aquatic Carnivorous Coleoptera or Dytiscidce. 



300. Hydroporus compactus, Clk., M.C. — Ovalis, Isevigatus, pernitidus, rufo- 

 testaceus, elytris paulo obscurioribus, his versus suturam crebre sat fortiter puiic- 

 tatis, humeris et lateiibus impunctatis. Long. 2,, lat. li m.m. 



This species is readily distinguished by its peculiar form, giving it somewhat the 

 aspect of one of the Noterini ; the elytra continue the outline of the thorax almost 

 without any interruption, and their hinder part is attenuate and narrow. The 

 prosternal process is broader than it is in the allies. 



In the male the antennee are more slender than in the female, and the front and 

 middle tarsi are slightly broader. 



This species varies in form; some specimens (especially those from Brisbane) 

 being more elongate than others. 



Eastern Australia, (from Melbourne to Brisbane). 86. 



301. Hydroporus gemellus, Clk., M.C. — Oblougo-ovalis, angustulus, subopacus, 

 rufescens, elytris vix obscurioribus, abdomine pectoreque nigricantibus ; elytris 

 versus suturam crebi-e punctatis ; tibiis anterioribus tarsisque posterioribus 

 gracilibus. Long. 3, lat. l\ m.m. 



This species is distinguished amongst its immediate allies, by its narrower form, 

 and its slender front tibiae, and slender and elongate tarsi. 



I have only seen two individuals of this species, which I believe are both females ; 

 both have lost the anteunpe except that in one the six basal joints remain, these 

 are rather slender. 



Australia, (proljubly the western portion ; South Australia, fide Clark.) 87. 



302. Bidessus muudus, n. sp. — Oblongo-ovalis, sat angustulus, subopacus, 

 rufescens, elytris vix obscurioribus, pectore nigricante, abdomine piceo ; elytris 

 crebre punctatis ; tibiis anterioi'ibus crassiusculis, tarsis posterioribus sat gracilibus. 

 Long. 3, lat. I5 m.m. 



Intermediate between Hydroporus gemellus and Bidessus biformis, distinguished 

 from the latter by its rather smaller size and narrower form, by the less obsolete 

 punctuation at the base of the elytra, and rather more slender legs. 



I believe I have the sexes of this species before me, and if so they are very 

 similar, the tarsi indeed show no difference, but the antennae of the male are slightly 

 more elongate ; in both sexes they are rather slender. 



Australia, (probably the west). 88. 



303. Bidessus biformis, n. sp. — 6 Oblongo-ovalis, nitidulus, fusculus, capite 

 thoraceque rufescentibus ; elytris basi sparsim apice crebre punctatis ; antennia 



