BY R. J. TILLYARD. 



773 



List B.— Species which habitually breed in still water (except 

 Anstrogomphus guerini, which does so occasionally). 



Name. 



Austrolestes lecla Selys ... 

 Austrolestes psyche Selys 

 Austrolestes annulosus Selys 

 Austrolestes analis Ramb. 

 Agriou lyelli Tillyard ... 

 Ischnura heterostu-.ta Burm. 

 Ischnura aurora Br. 

 Austroagrion cyane 

 Austrogomphus guerini Ramb — 

 Anax papuensis Burm. ... 

 ( Synthemi.s eustalacta eustalacta 

 \S. eustalacta tasmanica Tillyard 

 *S'. macrostigma orieiitalis 'lillyard 

 Procordulia jacksoniensis Selys 

 Hemicordulia tan Selys... 

 Nannophya dalei Tillyard 

 Austrothemis nigrescens Martin 

 Diplacodes bipunctata Br. 

 Diplacodes melanopsis Martin ... 

 Orthetrum caledonicum Br. 



Burm 



Tasmania. 





Total present in Southern Victoria 

 Total present in Tasmania 

 Total common to both ... 



19 

 15 

 H 



Percentage of Tasmanian to S.Victorian forms, 78*9%. 

 The contrast between the results given in these two lists is most 

 striking and calls for some definite explanation. How is it that so 

 few running-water forms, of the many found in Southern Victoria, 

 also occur in Tasmania? How is it, oii the other hand, that the 

 great majority of those still-water forms found in Southern Vic- 

 toria, also occur in Tasmania? How is it, in particular, that of 

 species in the same genus, equally common and widespread in 

 Southern Victoria, only the still-water species occur in Tasmania, 

 while the running-water species do not? For instance out of five 

 species of Austrolestes, only one, A. cingulatus, and that the most 

 abundant of all in Southern Victoria, does not occur in Tasmania ; 



