412 NEW GENUS AND SPECIKS OF ilAY-lLV FROM TASMANIA, 



dry climate, its sparse rivei-systems, many ot which e<?ase to liow during 

 driJiights, and its absence of lakes, is about as untavourable a region for their 

 development as can be I'ound anywhere. Now in New Zealand the dominant 

 faiuily everywhere is the Leplojihlebiidue, represented by the two g-enera Atalo- 

 plilebia and Deleatidium. The same family is dominant in Australia, the genus 

 Atalophlebia containing most ot the known Australian species of Mayflies. The 

 only other two families known in New Zealand are the Siphluridae and the 

 Epkemeridae, the former being represented by the three genera already men- 

 tioned at the beginning of this ]>aper, the latter by the single fine genus 

 Ichtliybotus, peculiar to New Zealand. Of the three New Zealand genera of 

 Siphluridae, Coloburiscu^ is represented in Australia by a single 

 Victorian species, AMeletus occurs on the Blue Mountains, though the species 

 has not yet been described, and now we see that the most remarkable genus of 

 all, Oniscigaster, is found to have its counterpart in tlie closely allied Tasmanian 

 genus described in this paper. As regards the genus Iclithi/botus, 1 have myself 

 collected larvae belonging to this genus in the Fish River, N.S.W. ; and there 

 is, in the National Museum at Melbourne, a fine subimago of another species, 

 not yet described, from the Upper Yarra River. 



The only element of the Australian Maytly fauna not present in New Zea- 

 land, or at any rate not yet discovered tliere. consists of two exceedingly .small 

 tropical sjiecies of the family Baelid-ae, one of which extends as far south as 

 New Soutli Wales, while the other is confined to the Northern Territory. It is 

 possible tliat a representative of tliis family may yet be found in the North 

 Auckland district in New' Zealand. 



Thus we see that the M.iyfly faunas of Australia and New Zealand are very 

 closely allied, in spite of the difference of climate. The same is true of the 

 Stonefly fauna, tlumgh tluit of Australia is only just beginning to be made 

 known. 



In concluding this paper, I wish to thank Mr. W. C. Davies, Curator of the 

 Cawthron Institute, for taking the excellent photogi-aph from which Plate xxxiv. 

 has been ]irepared. 



EXPLANATION OF PLATE XXXIV • 



(All figures s 2i). 

 B'ig. 1. 'J\isina>iop/iU'bia /acustris, n.g. et sp., male imago. 

 Fig. 2. ,, ,, ,, ,, female imago. 



Pig. 3. ,, ,, ., ,, male subimago. 



Fig. 4. ,, ,, ,, ,, female subimago. 



