( XXX ) 



theory is based on the supposition that Australia presents at 

 this time the phenomenon of an eastern and western fauna, 

 each wholly distinct from the other. This by no means 

 expresses the facts as I find them. The region is rich in 

 Lepidoptera , but they occur principally in certain limited 

 patches or tracts, either towards the sea-coast, or, if inland, 

 on hill-ranges, because there alone the average rainfall is 

 sufficient to maintain constantly the vegetation on which they 

 exist. All such tracts are therefore in a sense more or less 

 isolated, and may often contain numerous peculiar species. 

 It would therefore be more just to regard the region as 

 inhabited by a large number of separate faunae, each differing 

 more or less widely from its neighbours. Thus, in travelling 

 from Sydney to Perth by the south coast, one would pass 

 through about ten different faunas ; but the difference between 

 the first and sixth would not be greater than that between 

 the fifth and tenth. In other words, the rate of change is 

 uniform on the whole, though irregular in detail. One of 

 these faunae occupies the south-west corner of Australia, 

 within a line from Albany to Perth, roughly speaking ; it has 

 a good rainfall and very rich flora ; and it is this corner which 

 is usually intended when Western Australia is spoken of as 

 the only part visited. One has, however, but to cross the low 

 range whose foot lies ten miles inland from Perth, and the 

 change of fauna begins at once, there being a distinctly per- 

 ceptible increase in eastern forms. I may add incidentally 

 that the indigenous Lepidopterous fauna of Western Australia, 

 as a whole, consists mainly of Tineina, the other groups 

 being poorly represented in endemic species as compared with 

 Eastern Australia; the Geometrina stand next, but at a great 

 distance." 



Mr. Pascoe read a paper "On the genus Byrsops" a genus 

 of Curculionida3. 



The President announced that Lord Walsingham's collection 

 of Lepidoptera and their larvre, recently presented to the 

 Nation, would be exhibited in the Hall at the Natural History 

 Museum, South Kensington, until the end of June. 



