420 Records of the S.A. Museum 



intermediate femora with a spur or tooth near the apex ; intermediate tibiae about 

 If) times longer than the tarsi, the first segment of which is 1-5 times longer than 

 the second ; claws unequal, the longer one almost as long as the second tarsal 

 segment. Length, 10 mm. to 12 mm. ; width, 31") mm. to 4 5 mm. 



Hob. South Australia : Adelaide, Mount Lofty Ranges, South-Eastern 

 districts, etc., etc. (H. M. Hale), Myponga (A. H. Elston, etc.), Beachport (S. S. 

 Stokes); Northern Australia (Belgium Museum, etc., j\de Kirk.); Queensland: 

 Kuranda (R. W. Armitage), Cape York (Belgium Museum, etc., fide Kirk.); 

 New South Wales: Mittagong (A. M. Lea), Como (W. W. Froggatt) ; Victoria: 

 Macedon, Melbourne and Plenty River (Searle), Melbourne, etc. (Paris, Stock- 

 holm, and Belgium Mus., etc., fide Kirk.) ; Eastern Australia and Tasmania 

 (Paris Mus., fide Kirk.); Tasmania (A. Sirason) ; Western Australia (Kirk., 

 "meine Samml."); New Caledonia (type locality); Balade Ts. (Paris Mus., 

 fide Kirk.). 



The colour is variable; pale examples confined in aquaria eventually became 

 black, excepting for the head, legs, and part of the pronotrm. The life colouring 

 of a typical adult specimen is as follows : 



Notocephalon gray, laterally margined with translucent yellow, po.steriorly 

 with a bluish-black triangular marking, the basal angles of which touch the inner 

 posterior angles of the eyes; vertex suffused with bright, dark green (graminace- 

 ous) ; eyes dark rose ; beak and face graminaceous, the last-named laterally mar- 

 gined with dark yellow. Pronotum black on posterior half, gray marked with 

 black anteriorly, laterally tinged with green. Scutellum black, with a pale 

 yellow dash on each side. Remainder of upper side black. Underside of 

 abdomen black, with ventral carina and lateral edges graminaceous, and edges of 

 segments castaneous. Upper surfaces of legs green, in parts tinged with yellow ; 

 lower surfaces dark green, more or less marked with brown ; anterior femora 

 with two dark brown streaks beloAV and posterior femora with a dark brown stripe 

 beneath ; hairs brown. 



In the living bug the black first appears in patches, which spread until the 

 fine, uniform atrous colour is attained. For instance, on the scutellum a black 

 median streak, or a black triangular patch with its base on the anterior margin 

 of the scutellum, is first apparent; this patch grows larger until only a small 

 pale dash is left on each side (fig. 370), and finally even these pale portions 

 disappear. 



This species is taken farther from the banks than is Anisops, and rarely 

 congregates in large numbers, as do the last-named backswimmers. It has a habit 

 of clinging to submerged objects or floating at the surface in deep water. Its 

 food consists of any aquatic animal .small enough to be mastered, and it has been 



