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Annals Entomological Society of America [Vol. VI, 



It has already been noted that adult May-flies use their 

 legs little or none in walking and in many instances the fore 

 legs are not even used for support. In most males the fore 

 legs are enormously lengthened and when the insects are at rest, 

 they are often extended out from the head (PI. XLIV, Fig. 9). 

 The middle and hind legs brace the body, but they usually 

 lift only the front part, while the abdomen rests upon the sup- 

 porting surface (PI. XLIII, Fig. 6). The fore legs are necessary 

 structures in copulation and males of Palingenia which have 

 very short legs mate not in mid-air, but close to the surface 

 of streams. (Eaton). The legs' of • some May-flies have been 

 enormously specialized. The fore-legs of a South American 

 Campsurus are very long, (see Fig. 3), while the middle and hind 

 ones are but short stubs. In the fore legs there is a twist in 



Fig. 2. Male imago Campsurus (South America) showing rudimentary- 

 middle and hind legs. The setse not represented at full length here, are about 

 three times the length of the body. 



the joint which articulates the tarsus with the tibia. This 

 admits the supination of the tarsus and is evidently a modifica- 

 tion for clutching the female. 



