700 On Aquatic, Carnivoro^m Coleoptern or Dytiscidce. 



1096. Eretes {Ennec(es) australis, Er., M.C. — Testaceus, vcrtice nigi-o-signato, 

 elytris punctis magnis nigris impressis ; elytrorum humeris rotundatis, apice ad 

 suturam acuminate, epipleuris angustissimis ; prosterno processu acuto. Long. 14, 

 lat. 7 m.m. 



This species is closely allied to Dytisciis sticticus, but is really distinct ; it is 

 generally narrower in proportion, and has a more unicolorous appearance ; the 

 posterior femora and tibiae are more slender ; the punctures of the elytra are even a 

 little coarser than in D. sticticus, but they do not appear so conspicuously black, for 

 the black colour is entirely confined to each puncture, whereas in Dytiscus sticticus, 

 it generally also invades a small area round each puncture ; the thorax is never 

 marked with black ; the female has no trace of the depression at the edge of the 

 wing-cases, and its thorax scarcely differs in form from that of the male. There is 

 generally to be seen a small black dot at the edge of the wing-cases, but it is 

 much smaller than is usual in D. sticticus, and the black subapical fascia is generally 

 entirely absent, but is sometimes faintly indicated. 



Australia, (Melbourne, Sydney, Paroo liver. Port Denison, Cape York, West Australia). 955. 



11. 15. — Group Cybistrini. 



Swimming legs highly developed and very powerful, their tibiae especially short 

 and broad, and with the lower of their two apical spurs dilated, so that it is much 

 broader than (and frequently longer than) the superior one. The coxal notch of 

 the coxal processes very short, scarcely to be detected from the exterior. 



Any water-beetle belonging to this group is very readily recognized, the swim- 

 ming legs being different from those of any other of the Dytiscidae, but the species 

 are difficult to distinguish inter se ; the specific chai'acters are found in the size and 

 form, and in the presence or absence of a vellow band along the outside of the 

 wing-case ; this band may be nearly or entirely absent, or it may be present but 

 leave the epipleura and its raised margin of the same dark colour as the rest of the 

 surface, (in this case I speak of it as " vitta intramarginalis," or "vitta lateralis"), 

 or the yellow band may be larger, so that it extends to and includes the epipleura 

 (and in this case I describe it as " margo extemus testaceus "). The sexual cha- 

 racters are also of great importance in distinguishing the species, and the front 

 tarsi of the males should be carefully examined. In order to do this with satisfac- 

 tory results they must be damped and cleansed, and then flattened out so as to 

 place them in their natural position ; when the tarsi have been rendered quite 

 pliable, i he specimens should be placed on a piece of cork covered with clean paper, 

 and the tarsi flattened out and pressed down by means of needles pinned across 

 them in as horizontal a direction as possible, so as to exercise pressure on the foot 



