BY WALTER W. FKOGGATT. 257 



scutellum rounded. The wings are fully developed in both sexes; 

 the elytra or forewings longer than the abdomen, with stout 

 nervures, the costal with or without a stigma; the venation is 

 simple and constant, and of both generic and specific value. 

 From the primary vein run the radius parallel with the costal, 

 the cubitus which branches into an upper and lower arm, each 

 again bifurcated into a more or less regular cell at the apex; the 

 cubitus with or without a petiole; the hindwings simple. The 

 legs are formed for jumping; the coxse of the hind pair armed 

 with a rounded spine; the apex of the tibiae of the hind legs 

 armed with a fringe of fine spines ; the tarsi two, with large 

 double claws. The abdomen is composed of six segments. The 

 genitalia of the male comprise an upper and lower valve, two 

 curved processes known as the forceps, and an enclosed penis. 

 The female genitalia consist of two more or less elongate valves 

 enclosing the ovipositor. The form and structure of the genital 

 organs are also of use for specific characters, and are constant in 

 each species. 



The colouration and size are not constant. Low says, with 

 reference to the European species (18), that not only are there 

 differences in the colour according to the age of the insects, but 

 the same species on a different food-plant varies; and that the 

 successive generations change with the seasons in both particulars. 

 In Australian species so far I do not find any perceptible differ- 

 ence in the successive broods (many of which live all through the 

 year), probably on account of the comparatively uniform climate; 

 but the colouration is very variable in some species, particularly 

 in those hiding under bark or crawling upon the foliage in their 

 larval state, while the males are often the smallest. Though 

 some do not vary in the least, being distinctly marked when they 

 emerge from the pupa?, others often take several days to attain 

 the dark markings upon the wings, and these vary and fade away 

 to the faintest tinge of brown in individuals of the same brood; 

 pale yellows become ochreous. and browns black. After a time 

 many of the richest colours fade or change into darker tints. 

 17 



