416 On Aquatic Carnivorous Coleoptera or Dyti.scidce. 



In the male the front and middle tarsi are a good deal broader than they are in 

 the female, and the front tibiae have a slight excision on the inner edge below the 

 middle ; the middle tibiae also have their lower portion excised inwardly. The species 

 is very closely allied to Necterosoma regulare, but is less convex, has the sides of 

 the thorax quite simple, and the male characters rather more developed. 



Australia, 437. 



I. 39.— Genus MACROPORUS. 



The hind tibia has oidy the serial punctures on the infuro- external aspect ; the 

 swimming legs are well developed, their femora being stout, and their postero- 

 external angle sharply defined ; the terminal portion of tlie epipleura is rather 

 broad, and the genicular area is not limited by a raised line. The mesosternal fork 

 does not connect with the intercoxal process of the metasternum. 



The six species are found in Australia and Tasmania ; they are robust and large 

 insects for the tribe ; and have the best developed swimming legs of any Hydroporini. 



444. Hydroporus howittii, Clk., M.C. — Ovalis, minus latus, anterius angustatus, 

 nitidus, tenuiter brevissime pubescens, testaceo-ferrugineus, elytrorum sutura 

 plagisque posterius coalescentibus nigris ; elytris basi sparsim obsolete, apicem 

 versus dense subtiliter punctatis ; coxis posterioribus sat fortiter punctatis. Long. 

 5i, lat. 3 m.ra. 



In the male the front and middle tarsi are much dilated ; the first joint of the 

 front ones is particularly broad, the second strongly transverse, the third broad 

 and not greatly developed, the claws of the fourth joint are very unequal, the 

 anterior one being much the shorter and very abruptly curved. The female is not 

 quite so shining as tlie male and has the punctuation of the elytra denser. The 

 species does not appear to be a very variable one, though the colour of the under 

 surface varies from clear unicolorous red, to a red clouded with infuscations here 

 and there. 



Tasmania, Australia. 413. 



44.^. Hydroporus hamatiis, Clk., M.C. — Oralis, robustus, tenuiter pubescens, 

 dusniti vel opacus, colore variabilis, pedibus antennisque riifis, his versus apicem 

 fuscis, elytris fere sequaliter, subtiliter sat crebre punctatis ; coxis posterioribus sat 

 fortiter punctatis; abdoniiiie obsolete punctate. Long. 5j, lat. 3J m.m. 



