125 



the Dytiscidce (in which he states that he can give no informa- 

 tion about H. Gollaris) he would have formed a distinct genus for 

 them. I am not in a position to do so myself as I have not made 

 a sufficiently special study of the Dytiscidce to enable me to 

 furnish a satisfactory diagnosis without treating a male example 

 in a manner that my unique male would not bear, and therefore 

 I shall leave the species in A7itij)orus remarking however that it 

 differs from all those which Dr. Sharp placed in that genus in 

 respect of the sculpture of its pronotum (the lateral margins beino- 

 very widely thickened and raised, witli a sulcus or deep stria 

 separating the marginal from the discal portion) and in respect of 

 its sexual characters. The front tibia3 of the male have an 

 external median tooth similar to, but a little smaller than, the 

 tooth on the middle tibia3 of A. Blakei ; the front tarsi are some- 

 what feebly dilated and a little longer than those of the female • 

 my specimen has lost one each of the front and middle tarsi, on 

 the remaining ones I can find but one claw, though I am suspi- 

 cious of a claw having been broken off the middle tarsus. The 

 front tarsus seems to have its claw springing directly from the 

 apex of the third joint as though the basal part of the claw 

 joint were wanting, but it is quite possible that that appear- 

 ance would be found to be deceptive if a fresh specimen whose 

 tarsi would bear manipulation could be examined. The posterior 

 tibiae and all the femora are unarmed. In one ot the specimens 

 mentioned above the base of the pronotum is rufous at the sides, 

 which suggests the idea of identity with H. gravidus, Clk. (also 

 described from Port Essington) and I feel no doubt that 

 H. undecim-macidatus, Clk., is closely allied, if not a variety of 

 the same species. 



NECTEROSOMA. 



N. costiperme, Lea. This insect is no doubt identical with 

 //. pe7iicillatus, Clk., one of the commonest and most widely dis- 

 tributed IS well as most variable of the Australian water beetles. 

 Dr. Sharp, in his work on the Dytiscidce of the world, includes 

 under the name forms with and without elytral carinte, in which 

 I have no doubt he is right as I find that the forms with strono-ly 

 carinate, and those with non-carinate, elytra are connected by 

 forms in which the elytral carinse are more or less feeble. Ev^en 

 if the carinate forms represent a species distinct from the non- 

 carinate ones, however, it was the carinate form that Clark 

 described under the name Hydroporus penicillatus and therefore 

 the non-carinate form, if either, is the one that would need a new 

 name. 



PLATYNECTES. 



p. subcenescens, Lea. Mr. Lea has been good enough to send 

 me a specimen of this insect. He distinguishes it from ce)iescens, 



