362 On Aquatic Carnivorous Coleoptera or Dytiscide. 
300. Hydroporus compactus, Clk., M.C.—Ovalis, levigatus, pernitidus, rufo- 
testaceus, elytris paulo obscurioribus, his versus suturam crebre sat fortiter punc- 
tatis, humeris et lateribus impunctatis. Long. 2s, lat. 14 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 alles. 
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.—Oblongo-ovalis, angustulus, subopacus, 
rufescens, elytris vix obscurioribus, abdomine pectoreque nigricantibus ; elytris 
versus suturam crebre punctatis; tibiis anterioribus tarsisque posterioribus 
gracilibus. Long. 3, lat. 12 m.m. 
This species is distinguished amongst its immediate allies, by its narrower form, 
and its slender front tibize, and slender and elongate tarsi. 
I have only seen two individuals of this species, which I believe are both females ; 
both have lost the antenne except that in one the six basal joints remain, these 
are rather slender. 
Australia, (probably the western portion ; South Australia, fide Clark.) 87. 
302, Bidessus mundus, n. sp.—Oblongo-ovalis, sat angustulus, subopacus, 
rufescens, elytris vix obscurioribus, pectore nigricante, abdomine piceo ; elytris 
erebre punctatis ; tibiis anterioribus crassiusculis, tarsis posterioribus sat gracilibus. 
Long. 3, lat. 1¢ 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 antenne of the male are slightly 
more elongate ; in both sexes they are rather slender. 
Australia, (probably the west). 88. 
303. Bidessus biformis, n. sp.—dé Oblongo-ovalis, nitidulus, fusculus, capite 
thoraceque rufescentibus ; elytris basi sparsim apice crebre punctatis; antennis 
