416 On Aquatic Carnivorous Coleoptera or Dytiscide. 
In the male the front and middle tarsi are a good deal broader than they are in 
the female, and the front tibize have a slight excision on the inner edge below the 
middle ; the middle tibize 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 only the serial punctures on the infero-external aspect ; the 
swimming legs are well developed, their femora being stout, and their postero- 
external angle sharply defined; the terminal portion of the 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. 
54, lat. 3 m.m. 
In the male the front and middle tarsi are much dilated ; the first jomt 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 the 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. 
445. Hydroporus hamatus, Clk., M.C.—Ovalis, robustus, tenuiter pubescens, 
dusniti vel opacus, colore variabilis, pedrbus antennisque rtifis, his versus apicem 
tuscis, elytris fere zequaliter, subtiliter sat crebre punctatis ; coxis posterioribus sat 
fortiter punctatis ; abdomine obsolete punctato. Long. 53, lat. 35 m.m. 
