On Aquatic Carnivorous Coleuptera or Dijtiscidw. 413 



joint. The mesosteriuil fork is not connected with the intercoxal process of the 

 metasternum. 



The species ' are Australian and Tasmanian. 



It should be noted that the Australian and Tasmanian genus Sternopiscus 

 likewise has the front tarsi evidently five-jointed, but it has a very different structure 

 of the mesosternum, (see p. 384). 



4oG. Hydroporus penicillatus, Clk., M.C. — (Species pervariabilis) — Brevis^sime 

 pubescens, supra et infra densissirae subtiliter punctatus, subopacus ; elytris 

 ssppius longitudinaliter carinatis, sed interdum omnino requalibus ; tarsorum 

 anticorum articulo tertio brevi. Lono-. 4, lat. 24 m.m. 



The male is usually rather larger than the female, and has the front and middle 

 tarsi moderately dilated, the front tibiae are slender, and have a slight but distinct 

 notch in the middle of the inner edge, the middle tibiaa are a little curved. The 

 species is excessively variable, in colour, sculpture, and even in outline. Individuals 

 from Tasmania ai'e black, with the head yellow, and the sides of the thorax and 

 the outer margins of the elytra also of that colour, the legs and antennae are also 

 yellow with the outer portion of the latter infuscate : these dark individuals have 

 an acutely elevated carina on the middle of the elytra. Individuals from West 

 Australia present the other extreme ; they are entirely pale yellow, with the base 

 of the thorax and some lines on the elytra black, and there is no trace in some of 

 these individuals of any unevenness on the elytra. Intermediate specimens in all 

 these points are found, the variations being ajtparently rather constant in each 

 locality. The male characters do not vary much, but the Tasmanian individuals 

 of that sex have the front tarsi broader than those from Swan River. The female 

 always has the front tarsi rather broad ; each of the three basal joints being as 

 broad as, or rather broader than long. 



Tasmania, and Australia. 430. 



437. Hydroporus darwinii, Bab., M.C. — Ovalis, omnium densissime brevissimeque 

 pubescens, densissimeque punctatus, opacus, sordide rufus, prothorace basi 

 elytrisque signaturis confluentibus nigris ; corpore subtus densissime punctato, 

 omnino opaco : tarsorum anticorum articulo tertio elongato, basi tenui. Long. 41, 

 lat. 2| m.m. 



The male has the anterior and middle tarsi moderately broad ; the front tibiae 

 are moderately broad, and have a deep notch on the middle of their inner edge, 



* In addition to those of wliich the characters are now given, tlie following also belong to the genus : 

 Necterosoma flavicolle, Macl. (No. 1496), ? = No. 441; Australia. — Necterosoma vittipenne, Macl. (Nc. 

 1497),!= No. 43G; Australia. 



3 H» 



