306 Rev. F. D. Morice's Notes on Australian Sawflies. 



tion and climates of certain parts in both arc known to 

 have something in common, and may be alike adapted 

 to the occupation of somewhat similar groups. The 

 Aculeate Family of Thynnidae is. 1 believe, also limited 

 to these two Realms. 



To judge from the evidence of Distribution and we 

 have really no other evidence to go by it is hardly con- 

 ceivable that the Sawflies of Australia can have arrived 

 there otherwise than from Arctogaea, by way of the Oriental 

 Region, and travelling entirely overland. Even if. in very 

 ancient periods, " land-bridges " or " belts " may have 

 connected Neogaea and Notogaea by way of Africa, or 

 Oceania, or an extension of the Antarctic Continent, we 

 do not know that at thai time any Sawflies existed at all, 

 nor do any of the districts through which they would have 

 passed contain now. so far as is known, any evidence what- 

 ever of such migrations. Africa is the only one of them in 

 which at present any Tenthredinidae are normally to be 

 found, and not a single African Tenthredinid has the least 

 appearance of special affinity to Notogaeic or Neogaeic 

 forms: it is hardly too much to say that from Algeria 

 and Egypt to the (ape the whole " fades " of every 

 species and genus indicates a comparatively speaking 

 not very ancient Holarctic origin ! Again, much as 

 the present Arctogaeic Sawflies differ in certain respects 

 from those of Notogaea and Neogaea, there is so much 

 essential agreement in the general structure and instincts 

 of the whole Sub-order, that it is impossible to doubt thai 

 all must have radiated out from one original centre of 

 distribution: and it is most unlikely (taking all facts into 

 consideration) that such centre was anywhere but in 

 Arctogaea. All that is most strange and exceptional in 

 the characters of Notogaeic and NTeogaeic Sawflies can be 

 probably accounted for by their long separation from their 

 Holarctic relatives, during which separation they have 

 lived under dillerent conditions, and no doubt undergone, 

 in consequence, quite differenl modifications of structure, 

 instincts, etc.. in successive generations; and. as might be 

 expected, the Notogaeic Sawflies are, on the whole, much 

 more abnormal than those of Neogaea, the former only 

 having been completely isolated since Tertiary times. 



Although I have ventured to express the above opinions 

 with some confidence, 1 must admil that they rest mainly 

 on circumstantial and not altogether satisfactory evidence 



