38 THE VICTORIAN NATURALIST, [Vol. XXIV. 



devour the pupa, after having pierced the cocoon at the bottom. 

 The moth which I reared from the caterpillar does not seem to 

 have been described yet. 



A curious fact about the two genera Gicophylla and Polyrhachis 

 is that, although both use their larvae fur spmning, the pupa of the 

 first-mentioned are naked, while those of the latter are provided 

 with a cocoon. 



[This paper was forwarded through Mr. F. P. Dodd, of Kuranda, 

 North Queensland, who has added the following note: — "Mr. 

 Jacobson's observations agree well with my own. I have found 

 caterpillars of two species of whitish pyrales, with similar cocoons, 

 in the nests of CE. virescens. Though I have frequently seen dead 

 creatures in the vicinity of the ant habitations, 1 have only once 

 seen the ants on one — an ibis — and then they were there after 

 the beetles (Staphylinidse, &c.), infesting it. A dead snake on a 

 tree in occupaiion of the ants dried here without my ever seeing 

 a green ant on it, though I saw it dozens of times." — Ed. Vict. 

 JVat.] 



An Introduced Noxious Water-weed. — At the May meeting 

 of the Club I exhibited living and dried specimens of ELodea 

 canadensis, Michaux (syn. Anacharis alsinastruvi, Babington), an 

 aquatic plant belonging to the Nat. Ord. Hydrocharidcce, a native 

 ot North America, and which is variously known as " American 

 Water-weed,'' " Babington's Curse," "Choke-pond Weed," "Snake 

 Weed," and " Water Thyme." The plant is well known to 

 microscopists, owing to the interestmg and distinctly marked sap 

 movements which sections display, and some particulars regarding 

 It may be of interest. Some little time ago Mr. W. R. Guiltoyle, 

 Director of the Melbourne Botanical Gardens, had his attention 

 drawn to this plant as growing luxuriantly and fast becoming a 

 menace to all other vegetable aquatic life in the small lake of the 

 Japanese garden at the Treasury Gardens, Melbourne. It was 

 only by emptying the lake, and thoroughly cleaning every particle 

 of the plant from the banks, that the Director endeavoured and 

 hoped to banish this possible scourge from our midst. Its 

 appearance could no more be accounted for in Melbourne than 

 when it was first discovered, almost simultaneously, in different 

 parts of Britain about the middle of the last century. Records 

 show it to be wonderfully rapid in growth, and readily propagated 

 by stem or root division. It has proved itself a great curse 

 wherever it has found a hold in Britain and elsewhere, by 

 destroying the beauty of artificial lakes, and the usefulness of 

 canals and reservoirs and other watercourses and areas. Al- 

 though it is stated water birds eat the plant, the wider propagation 

 of it is thereby insured, as these fowls pull and divide pieces in 

 the process. The object of showing the specimens was to enable 



