BY R. J. TILLYARD. 737 



9. Similar to male, but of stouter build. Eyes brownish; 

 notum touched with brown; abdomen fairly stout, cylindrical, 

 black with a slight tinge of metallic green. Ovipositor project- 

 ing further beyond appendages than in the type. 



Hah. — Common on all the mountain-brooks; rare on the larger 

 rivers and coastal lagoons. Race pusillus occurs, together with 

 the type-form and intermediate forms, at Bridgetown, Wilgarrup, 

 and proba,bly in many other localities. It also occurs at Albany; 

 all the specimens in the Macleay Museum, Sydney, from Albany, 

 are of the race pusillus. 



It is generally found sitting about with outspread wings on the 

 stems of grass and reeds overhanging running streams. Often 

 several specimens could be netted at once by a sweep of the reed- 

 clumps. Its flight is weak and slovv^, and it is easily captured, 

 even with the hand. The race j^usilhts often sits with its wings 

 closed, a peculiarity shared by A. griseus, which is sometimes 

 found in that position. 



It appears to me that pusillus holds very much the same rela- 

 tion to the type miniynus as griseus does to icteromelas. But in 

 the case of the two common Eastern species the intermediate 

 forms are absent, and the two species easily separated, though 

 in some districts rather small forms of icteromelas occur. In 

 pusillus we have a species in course of formation. Put pusillus 

 and minimus side by side, and one sees two absolutely distinct 

 species. But take two dozen of the insects from any one locality, 

 and they can be arranged so as to link together, gradually and 

 almost insensibly, the two extreme forms. The t3'pe-form minimus 

 can be easily distinguished from A. griseus oi the Eastern States, 

 to which it is closely allied, by its smaller size, more slender 

 build, the lack of thoracic markings, the shape of the appendages, 

 which are much slenderer, and the lack of grey bloom on the 

 abdomen. The race pusillus approaches griseus closely in having 

 grey bloom on the thorax and part of abdomen, but it is less 

 than half the size of griseus, and differs from it in other respects 

 as the type does. 



