BY R. J. TILLYARD. 



303 



Some interesting deviations from the normal jugate type ma}' 

 now be noted in the Hejnalidce : — 



(1) In the genus Pielu.% the jugum is a hard chitinous rod, 

 somewhat truncated at its tip, and placed so as to project de- 

 finitely beneath the anal area of the forewing (Text-fig. 12). It 

 is quite impossible to make this rod pass under the costa of the 

 hindwing, either in the living or freshly-killed insect. But it 

 will fit quite easily abovfi the costa of the hindwing, near the 

 base, where there can be found, in specimens that have been on 

 the wing, a deep groove worn in an oblique direction in the dense 

 hairs that clothe the area around the humeral cross- vein. 



It would appear, then, that this genus differs from the rest of 

 the family in having the juguin lesting above the costa, not 

 beneath it, and also in the structure and position of the organ 

 itself. We should, therefore, regai'd this genus as highly 

 specialised. 



(2) l7i the genus Lpfo, some specimens show a very weakly 

 formed jugum of very 



small size for the bulk 

 of the insect: while 

 others have none at 

 all. The bases of the 

 wings are densel}' 

 clothed with long, soft 

 hairs. The method of 

 coupling in these mag- 

 nificent insects, which 



are said to have great Text-fig. 12.^ 



powers of flight, appears to be practically amplpxiform, the anal 

 field of the forewing being bounded anteriorly by a ver}^ strongly 

 developed lA, and overlapping the costa of the hindwing to a 

 considerable extent in flight. 



(3) In the small moths of the genus Frau.% the jugum is very 

 short, yet it undoubtedly secures the costa of the hindwing in 



* Jugum of P ie/ as hi/a/inatii)i Don., 9 , viewed from beneath, to show 

 natural position under anal area of forewing; ( x 6). 



