00 : August, 



" The pale fascijB are broadei', the posterior one runs iu a straight 

 " direction towards the anal angle, whereby the dark middle fascia is 

 "expanded towards the inner margin." 



Of irriguana, H.-S., he says — " Anterior wings with slightly curved 

 " costa and straight hind margin, olive-greenish, with more or less 

 " distinct dark fasciae bordered by pale leaden lines. TJnicolorous 

 " specimens of this species occur which are quite like sudetana, and 

 " only to be distinguished from it by the less curved costa, the rather 

 " straight but oblique hind margin, and the sharper pointed apex of 

 " the anterior wings. Sometimes the costal streaks and the leaden 

 "lines are almost entirely wanting, &c., &c." 



Now, I have a series of specimens of this groiip from different 

 parts of the Continent, labelled (rather promiscuously) metallicaiia 

 and irriguana. Some (bearing each name) are broad winged, with 

 curved costa ; hind margin not very oblique, and in the breadth and 

 disposition of the fascia; also, agree closely with the above description 

 of metalJicana. Others with narrower wings, straighter costa[andhind 

 margin, and very pointed apex, agree exactly with the description of 

 irriguana, and with our Scotch specimens, as also do Herrich-Schaffer's 

 figures, 42i — 5. These Scotch specimens all belong to the variety 

 without silvery lines (although Dr. White tells me that even these 

 are slightly perceptible when the moths are alive). The majority of 

 them are darkly marked as in Heinemaun's description, and a few are 

 almost unicolorous, closely resembling sudetana, Standfuss. I am 

 therefore satisfied that our insect is truly irriguana, and also strongly 

 disposed to the opinion that it is distinct from metullicana, Tliibn., 

 although the difficulty of deciding, from the similarity and parallel 

 variation of the species of this group, is so great, that I should not feel 

 at all surprised if the sight of series from new localities should com- 

 pletely upset the conclusions that have now been arrived at with no 

 little difficulty. 



As no detailed description of irriguana has been published in 

 this country, it may be worth while to append one, although that 

 already quoted from Heinemaun is very clear. 



Head, palpi, and thorax dark grcj. thickly sprinkled with pale yellowish soalcs ; 

 antennae dark grey ; fore-wings pale buff with an olive tinge, and with dark greyish- 

 brown markings ; basal blotch interrupted, produced on the fold almost to the 

 central fascia ; central fascia also sometimes interrupted above the middle, irregular, 

 toothed exteriorly. Beyond it is a blotcli at the anal angle, and an oblique cloud 

 across the apical region ; sometimes these unite and form a fascia before the hind 

 margin. On the costa towards the apex are three short streaks or spots ; cilia pale 

 ochrcous dusted with black ; hind-wings dark grey ; cilia straw-coloured, with a 

 dark hne at the base. • 



