230 
Mr^^ouis B. Prout on the 
median band to subterminal region ; terminal line dark, interrupted 
at the vein-ends; fringe concolorous. Hindwing rather small, fuscous 
grey, unicolorous. Underside somewhat paler, usually very w'eakly 
marked, with faint traces of the postmedian line on both wings, 
which, in one or two specimens, becomes a conspicuous dark 
line dividing a darker proximal from a lighter distal area, as in 
L. giacomellii, ab. angulata. 
La Paz, Mendoza, 4 1 ^ (September to November 
1905, at light, etc.), Balde, 1 $ (September 20, 1908), all 
collected by Mr. W. M. Bayne, who states (in litt.) that 
the moth sits with its wings rather closely folded to the 
body. The type La Paz, October 22), in coll. L. B. 
Prout, is a rather sharply marked form. The species is 
variable, not only in the respects indicated above, but also 
in the breadth of the median band, yet is easily recog¬ 
nised ; only a pale, rather worn $ (March 1903), with the 
“twin spots” pronounced, and a slight difference in vena¬ 
tion, presents a rather distinct aspect, and may be a 
separate, though closely allied species. 
A noticeable point in the venation of the ^s (excepting 
that last named), as also in the unique $ of L. tzaddi, is 
the curvature of M^ of the forewing, which arises from M 
rather steeply, and rather near M^, afterwards curving into 
its normal position. This formation is foreshadowed in 
the $ of L. pax, and in many species of the group (par¬ 
ticularly in Chesias), but seldom so pronounced ; it reaches 
its extreme development in Neocliesias, described below. 
Veins C and SC of hind wing are, in the ^ of L. pax, 
rather far apart towards the base, gradually converge, and 
anastomose at a point near the end of the cell; this is a 
slight exaggeration of the structure familiar in the ^ of 
the genus Carsia. I do not consider this necessarily 
generic; compare the variation in Anaitis. 
58. Lithostege (?) tzaddi (Prout), nov. sp. 
(Plate XLVIll, fig. 6.) 
$ . 26 mm. Face somewhat jirominent, tufted ; palpus moderate, 
strongly rough-scaled ; antenna nearly simple, pubescent; (legs lost). 
Head, thorax and palpus grey (white mingled with fuscous), whiter 
beneath. Groundcolour of forewing whitish, densely irrorated with 
fuscou.s, markings darker fuscous, mostly somewhat ill-defined : a 
difi’use subbasal line, very oblique from costa, acutely angled on sub¬ 
median fold, thence oblique basewards, but obscured by the dark 
