Monograph on Argyresthia. v 



bushes, and without doubt also on species of plum and pear. When full-grown they 

 descend by a thread to the earth, ond there change to the pupa under moss and dried 

 leaves." 



Fabricius's description, " Alae anticae argenteae nitidae, lineola baseos lunulaque 

 communi fuscis," leaves no doubt of this being his insect ; and I am rather of opinion 

 that it is also the tetrapodella of Linneus, whose words, " Tinea grisea, linea longitu- 

 dinali nivea, lunula fusca postice dissecta," are almost identical with those of Fabricius, 

 the greatest discrepancy arising from his insect being gray and that of Fabricius sil- 

 very ; but as the species varies from pale tawny to silvery -white, that is of little im- 

 portance. The " lunula fusca," the character of the species, which distinguishes it 

 from all its congeners except purpurascentella, must prevent the Linnean description 

 from applying to any other, and it certainly cannot apply to spinosella, which Zeller 

 unhesitatingly calls the tetrapodella of Linneus, but unfortunately states no reason for 

 so doing. 



At the same time, while giving my reasons for considering this species the tetrapo- 

 della of Linneus, I am unwilling to increase the complexity of the nomenclature in 

 this genus, by at once superseding the Fabrician name; but I think it probable that 

 it must eventually sink and the Linnean name be retained. There is unfortunately 

 no specimen of tetrapodella in the Linnean cabinet. 



Sp. 3. purpukascentella, Stainion. 



Expansion of the wings 4 — 5 lines. Head white, with a few gray hairs. Face 

 white. Palpi whitish. Antennae white, annulated with dark fuscous. Thorax white, 

 with the sides purplish fuscous. Abdomen fuscous. Legs whitish. Tarsi whitish, 

 spotted with fuscous. Anterior wings purplish fuscous, inclining to pale ochreous on 

 the costa ; the inner margin is white to the anal angle, interrupted rather beyond the 

 middle by a curved dark fascia, which is hardly traceable across the wing, yet it ap- 

 pears to curve towards the apex as in the preceding species ; the basal portion of the 

 white inner margin does not expand just before the fascia, as in nitidella, but is con- 

 tinued almost straight to the fascia ; a dark streak proceeds from the base, extending 

 about a third of the wing, as in nitidella ; the costa is delicately spotted in its whole 

 length, but towards the apex are two larger pale spots, as in nitidella; beyond the 

 fascia the colour of the wing is deeper than towards the base : cilia purplish fuscous. 

 Posterior wings grayish, with paler cilia. 



This species approximates so closely to the preceding that I at first took one of my 

 specimens for a variety of it : it is, however, distinguished by the different ground- 

 colour of the anterior wings, and by the white inner margin not expanding before the 

 fascia. In colour it somewhat resembles spinosella and semifusca, but differs from 

 them in the extremely curved position of the fascia ; besides which it has not the 

 ochreous base of spinosella, nor the rich concolorous appearance of semifusca. 



My finest specimen (that described) I beat out from among birches, along with 

 retinella, near Canon, Stirlingshire, on the 18th of July. My other specimen I beat 

 out of a hawthorn-hedge, at Sheffield, on the evening of July 22nd, along with niti- 

 della and ephippella: this specimen is much smaller than the one described and 

 somewhat wasted, and on the left wing the fascia does not touch the inner margin. 



