860 Oh Aquatic Carnivorous Coleoptera or Dytiscidce. 



Ccelambus, from which it differs by the terminal joints of the front tarsi, and by 

 the gi-eater separation of the articulations of the swimming legs. 



The species are found in the East, in India, and Egypt. The genus is not a very 

 natural or satisfactory one, as Hydroporus solieri is not so Hyphydroid as its allies ; 

 there can be little doubt that other allied species remain to be discovered, and the 

 separation of the species into two distinct aggregates would be at present premature. 



I. 33.— Genus PAROSTER. {Vide j). 391.) 



Three species from Australia form this aggregate ; the individuals resemble 

 greatly ordinary Hydropori, but have the upper surface more convex transversely 

 than is usual in the species of the genus Hydroporus : the size is rather small, 

 (3 or 4 m.m. of length) the form convex, rather short, but not very broad ; the 

 surface is without pubescence. The head is not in the least margined in front ; 

 the prosternal process is compressed laterally, strongly carinate, and elevate along 

 the middle ; the mesosternum does not connect with the inter-coxal process of the 

 metasternum ; the hind coxae have a moderate extension in the anterior direction ; 

 their processes are peculiar, the intra-rimal portion being prolonged considerably 

 beyond the extra-rimal portion ; the coxal lines are effaced in their posterior part, 

 the coxal border is excessively minute with slender, acute, outer angle, and the 

 articular cavities are much exposed ; the structure of these parts may be briefly 

 described by saying, that the articular cavities are rather widely separa,ted, and 

 that there exists a quite distinct, indeed rather large coxal notch, notwithstanding 

 the small size of the terminal portions of the coxal processes. The hind legs are 

 slender, their tibiaa are slender as well as a little crooked below the knee ; the 

 genicular area of the wing-case is bordered behind by a raised line ; the inner face 

 of the wing-case is without any trace of apical ligula : the basal ventral segment 

 is not soldered to the coxje. 



The species are peculiar to Australia and are very rare in collections at 

 present. 



These obscure and unattractive insects prove to be of considerable interest when 

 examined and compared, and to be much isolated : they have resemblances to 

 Bidessus (of the Bidessini), as well as to Ccelambus of the Hydroporini ; the 

 approximation to Bidessus consists in the form of the articular poi'tions of the hind 

 coxae, which may be described as that which exists in Bidessus but rendered more 

 conspicuous by the wider separation of the articular cavities : the slender hind 

 tibiae also are such as exist in Bidessus. The genus differs from Ccelambus by 

 the peculiarities of the coxal processes, and by the want of ligula on the inner 

 face of the wing-case. 



