H YD ROC A MPID.^—A CENTROPUS. 301 



divided broadly iu the middle ; body pale green or whitish- 

 yellow, with a broad, ill-defined and cloudy, dorsal smoky- 

 black stripe, which is interrupted on the eleventh segment 

 and does not appear on the thirteenth ; no visible lines ; 

 spiracles small, black ; raised dots very indistinct ; leo-s 

 smoky-black, prolegs of the colour of the body. 



October till May, and a second brood in July ; on 

 Potamor/don pcctinattcs, P. pcrfoliatus, P. crisjms, P. lucens, 

 Trwpa nutans, Eydrocharis morsus-raim Ceratophy/lum 

 (lemersum, and other submerged water plants; living only 

 under water. 



Pupa apparently not described. In a white silken cocoon 

 in the axil of a leaf of one of its food plants, under water. 

 Mr. Edwin Brown says that it possesses the usual Lepidop- 

 terous characters, and that three spiracles on each side are 

 remarkably prominent. 



The moth sits during the day upon weeds close to the 

 surface of water, under stones at its edge, or especially upon 

 partially submerged sticks, sometimes congregating thickly 

 on the undersides of the latter. When so sitting it quite 

 disregards the necessary immersion caused by drawing the 

 weeds or sticks through the water towards one, but if 

 shaken or knocked off will buzz along the surface till it 

 finds something to cling to. In crossing one of the Norfolk 

 "broads" or lakes I have been much interested to see the 

 disturbed males, a dozen at a time, making short zigzag 

 tacks, as they buzzed over the water in pursuit of the boat 

 by which they had been disturbed, till they overtook and 

 climbed up its stern-post and rudder. These were all males, 

 and subsequent close searching of the floating and surface 

 weeds, and of the submerged plants, furnished but one 

 female, and that of the wingless form and moribund. 

 Possibly the females fall from the plants to the bottom of 

 the water when disturbed. They seem to be quite at home 

 in that element. Winged females were formerly taken at 



