nOAKMID.-E—STREAIA. 5 



black or brown-black ; hind margin dusted with the eame, 

 and the whole surface broken up, by four somewhat equi- 

 distant, transverse stripes of the same colour, into a reticulated 

 or sieve-like pattern (hence the name) ; extreme hind 

 margin edged with a sharp line of the same dark colour, with 

 which also the white cilia are regularly chequered. Hind 

 wings rather elongated, slightlj'- angulated at the apex, and 

 very obtusely so in the middle of the hind margin ; in colour 

 and markings accurately similar to the fore wings, except 

 that the transverse stripes are three in number only ; extreme 

 hind margin edged by a faintly scalloped purple-black line, 

 similar bars from the nervures chequering the white cilia. 

 Female smaller, often considerably so, the ground colour 

 sometimes paler, and markings darker, otherwise similar. 



Underside an accurate repetition of the colouring and 

 markings of the upper, except that the markings are of a 

 more yellow-brown colour. Body and legs pale yellow, 

 dusted with purple-brown. 



There is considerable variation in this species in ground 

 colour, from pale yellow to dusky yellow or to silvery white, 

 this last being more particularly an Irish form ; also in the 

 form and position of the transverse stripes ; the first and 

 second sometimes being united, partially or wholly, and the 

 third and fourth in a similar manner ; or the fourth broadened 

 into a considerable irregular band ; or otherwise diminished 

 and broken. A specimen in my own collection has the first, 

 second and third stripes massed together into a very broad 

 but hardly perfect band. One in Mr. Sydney Webb's cabinet 

 has only a strong central stripe, the others being broken into 

 detached transverse spots. Another of the same character 

 has the stripe near the base ; a third has but two slender 

 stripes, one near the base, the other just before the hind 

 margin. In Mr. S. J. Capper's collection is one having on 

 fore and hind wings two broad bands each, and another 

 having three very slender stripes on the fore wings and one 

 on the hind, another being partially represented Ijy spots, the 



