302 Rsv. F. L). Morice's Notss on Australian Sawflies. 



important is the "Holarctic," which includes the greater 

 part of North America, all Europe, and the parts of Asia 

 and Africa adjacent to the Mediterranean Sea, Siberia, N. 

 China. Japan, and Central Asia. The parts of Asia nearest 

 to and north of Australia (India. South China, Sumatra, 

 Borneo, etc.) are the " ( Oriental Region." South Arabia and 

 South and Central Africa make up the " Ethiopian Region.*' 

 Madagascar is the centre of an isolated Region of its own. 

 And the " Sonoran Region *' separates — or, rather, bridges 

 over the interval which separates— Neogaea from Holarctic 

 America. The word " Holarctic " will occur frequently in 

 this Note, but the other Regions will seldom have to be 

 mentioned. I know their Sawflies only from Museum 

 specimens, but if the inferences suggested by these can be 

 trusted, the differences between Holarctic forms and those 

 occupying other Arctogaeic Regions arc not very striking 

 and negative rather than positive : i. c. the latter are 

 characterised chiefly by the absence or extreme rarity of 

 groups which are dominant in the North, and the places 

 of these are filled not by other groups peculiar to the Region, 

 but by a further differentiation and increase of certain 

 particular genera which are well represented in the Hol- 

 arctic Regioii also. In Africa, for instance, and perhaps 

 throughout the Ethiopian Region, forms identical, or nearly 

 identical, with Holarctic A/ye and Aihalia spp. seem in a 

 maimer to have made themselves paramount. (Pachylota, 

 Westw., originally described as from " S. Africa."' would 

 be a singular exception to the general rule, if we did not 

 know that this genus was really Neogaeic.) In the number 

 of well-differentiated "high" divisions (Families, Sub- 

 families, etc.) included in and often confined to it. the 

 Holarctic Sawllv Fauna far exceeds that of all the other 

 Regions taken together, and from this it is natural to infer 

 thai the Sub-order has been longest established there, and 

 that somewhere in this Region was probably the original 

 cent iv of its distributions, the Sawflies of the other Regions 

 being really descendants of such Eolarctic genera as haw 

 overflowed into them and succeeded in adapting themselves 

 to the new surroundings. Any genus which could not do 

 i his would remain, of course, confined to its original habitat, 

 or extend only in certain limited directions chiefly east- 

 wards or westwards, such movements involving no change 

 of climate, etc. 



But if. alter comparing t he Saw flies of various Arctogaeic 



