269 
Gcomctridae of the Argentine Rcpuhlie. 
or less pale-centred, but this phase of variation gives rise 
to an infinity of slightly ditferent forms ; the pale portion 
may be broader or narrower, sometimes broken into large 
costal and two small innermarginal spots, it may be only 
slightly paler than the rest of the band, or even on the 
other hand clear white—the most striking forms—or again 
it may be tinged with flesh-colour or almost reddish, 
slightly suggesting the type form of X. ferrugata, or with 
a somewhat more ochreous shade. In one or two speci¬ 
mens the areas placed proximally and distally to the median 
band are quite reddish. My single Mendoza specimen is 
of the ab. muscosata. 
Mr. Bayne tells me that this is the only Geometrid 
common in the winter in Buenos Aires. I find the dates 
range from March 31 to September 25, It is interesting 
that the only three species for which I have noted winter 
records from there— Hamviaptera tencra, Ochyria argentina 
and the present species—all belong to the Larentiinae, the 
sub-family which is so preponderant in Arctic and mountain 
regions, so comparatively deficient in representatives in 
tropical climes. 
109. Perizoma sordescens (Dognin). 
Perizoma sordescens, Dognin, Ann. Soc. Ent. Belg., lii, 18 
(1908). 
La Paz, Mendoza, September 18, 1903, one $ (VV. M. 
Bayne); Paltnira, one ^ (W. M. Bayne); both in coll. 
L. B. Prout; San Rafael, one in coll. A. F. Bayne. 
Dognin’s type was from Peru; I have compared my 
specimens therewith. 
A somewhat variable species in colour and in intensity 
of markings, but the median band seems constant in shape. 
My? is darker than my I have a worn specimen from 
Palmira, September 13, 1903, which is apparently a close 
relative, or likely even an aberration, of F. sordescens, but 
I cannot decide definitely until similar specimens are met 
with in better condition. It appears to have the median 
band entirely absent—an extreme of variation not unknown 
in some of the most variable of the Larentiinae{e.g. Perizoma 
niveata, Steph. = albidata, Schiff., Oporinia dilutata, Schitf., 
etc.); but it is harder to reconcile the position of a rather 
distinct subbasal band with the markings of P. sordescens ; 
on the other hand, the black subapical marks are typical 
