32 ox THE STUDY OF ZOOGEOGRAPHICAL REGIONS, 



Application of tlie Method to a Selected Region. 



Let us now take the Australian region and apply the method 

 of specific contours to it, as far as our records will allow us. 

 Probably no region has been so little worked: so that, if we are 

 able to obtain satisfactory results from somewhat meagre records, 

 we should be encouraged to expect even better results in regions 

 where the records are more complete. 



'Ihe groups will be selected from the Odonata, in which the 

 author has collected fairly complete records during the past nine 

 years. Our objects will be (l)to recognise which groups of 

 Odonata present ectogenic, entogenic, or palseogenic contours 

 respectively; (2) to try to discover whether distinct subtypes 

 exist within any of these three types. 



By reference to the map in the Plate, it will be seen that some 

 of the Papuan portion, and much of the Polynesian portion, has 

 been omitted from the Australian region. The records of the 

 Papuan portion are not complete enough, while the contours 

 exhibited do not in any case extend into that part of the Poly- 

 nesian subregion omitted. Owing to the small size of the map, 

 the inland continental limits of the various contour-lines have 

 been somewhat extended, otherwise they would appear too closely 

 crowded along the coast-line to be distinguishable on so small a 

 scale. 



A. Ectogenic Contours. — Transparency I exhibits the approxi- 

 mate specific contour of the genus Rhyothemis. This is a genus 

 of dragon flies with coloured wings, belonging to the subfamily 

 LibeUu/ina', and very distinct from its nearest allies. It is ento- 

 genic in the Oriental region, but has spread eastwards across 

 Wallaces line, appearing as a strong immigration stream into 

 the Papuan subregion and along the northern and north-eastern 

 coasts of Australia. One species (E. graphiptera) has spread as 

 far south as the Clarence River, in New South Wales, and reaches 

 also inland up to the 3,000 feet level in North Queensland. 

 Another (/i. phyllis chlo'e) reaches just into New South Wales at 

 Murwillumbah, and does not extend as far inland as R. graphip- 

 tera. A third {E. chaJcoptilon) has not been recorded south of 

 Gayndah. Two other species [R. resplendens and R. braganza) are 



