96 
OPORINIA. By L. B. Prout. 
lines of forewing variable in intensity; hindwing still lighter, unmarked or sometimes with a narrow, weak 
median band and traces of one or two lines outside it. Avatsha Bay and near Petropavlovsk, Kamtshatka, 
several and 5 $5, end of September and beginning of October 1908. 
44. Genus: Oporinia Him. 
(See Vol. 4, p. 194.) 
The revision already given (as quoted above) and the references contained therein have borne much 
fruit in directing attention to this very interesting genus, and most studious lepidopterists are now w'ell ac¬ 
quainted with the principal distinctions, particularly in the antennae and the genitalia. Especial attention 
may be called to the contributions by Wolff (Denmark), Nordstrom (Sweden) and Warnecke (Lower Elbe 
district), as well as to the biological studies of the English geneticist Harrison. The first-named, by careful 
micrometric investigations of a large number of 0. christyi and dilutata, has demonstrated the limits of the 
individual variability in the distance between the octavals and his measurements enhance, rather than di¬ 
minish, the general value of the distinction here shown. Hybridization has been found possible, even between 
dilutata and autumnata (See Journ. Genet., Vol. 3, p. 232 and Entom., Vol. 48, p. 1, 30) and between autum- 
nata or filigrammaria and their American cousin omissa Harrison (see Trans. Northern Nat. Un., Vol. 1, 
p. 135) and has yielded very interesting results, which cannot be detailed here. There is also in the typical 
section of the genus a strong tendency to produce little segregated groups or colonies which breed true and 
sometimes even show (minute) structural differences from their nearest neighbours; these Harrison, in order 
to avoid the misused terms “race”, “subspecies”, has called “microgenes” and he considers analogous to the 
forms well-known to botanists in the genera Hieracium, Rubus, etc. The tongue in Oporinia is developed 
but not (as was stated in Vol. 4) the frenulum. The resting posture differs from that of any other Geometrid 
observed by Oudemans in that the costal margin of the hindwing projects in front of that of the forewing. 
dilutata. 0. dilutata Schiff. (= nebulata Thnbg.) (Vol. 4, pi. 9 f). The discovery of the larva and imago at Al- 
barracin has added the Iberian Peninsula to the range of this species. Its occurrence in Scandinavia is now 
confirmed; Nordstrom records it from the southern third of Sweden and from the neighbourhood of Oslo. 
He has studied Thunberg's type and paratypes of his nebulata and shown conclusively that, although the 
latter series comprises a mixture, the name belongs to a specimen of dilutata. Thus its citation to autumnata 
must be deleted from p. 196. The name nebulata (preferred by Nordstrom) is not a homonym, as was there 
assumed; but it is 8 or 9 years younger than dilutata. Schiffermuller's dilutata was an oak-feeder and the 
traditional interpretation should be conserved; only if the Swedish dilutata should prove a distinguishable 
regressa. subspecies from the Austrian will the former stand as d. nebulata. — ab. regressa Harrison. Ground-colour 
blue-black, markings practically obsolete, median area showing a broad silvery band. Team Valley, Durham. 
j rax inaria. — f. (microgene) fraxinaria Harrison was defined as much smaller than typical dilutata of the same districts 
(N. England), bluish-grey, glossier, with practically no markings but not melanic, the time of appearance 
30 September to 20 October (dilutata middle of October onward), the egg slightly smaller, hatching earlier, 
the larva green, never purple-marked, nearly always feeding on ash. Octavals as in christyi , labicles head 
intermediate between that and dilutata, the valves much as in dilutata but smaller. It has apparently been 
robsoni. subsequently suppressed (to christyi?). — hybr. robsoni Harrison (dilutata $ x autumnata $) is intermediate 
between the parents in several respects, including the antenna; but on the whole the are slightly nearer 
to autumnata and the $$ intermediate or towards dilutata; both sexes have the white V at the furcation of 
the median with its 2nd branch well developed. 
christyi. 0. christyi Prout (Vol. 4, pi. 9 f). Heydemann points out that the dilutata, quadrifasciata and af- 
finiata of Borkhattsen, afterwards merged by their author, all occurred commonly together in beechwoods 
in October, at times in copula, and may most probably designate aberrations of christyi, but does not think 
that any certainty can be reached; the first of these names would be a misidentification of the preceding species, 
the second a homonym, but it is not improbable that affiniata may need to be revived in place of christyi. The 
distribution is certainly wider than was given in our earlier volume (S. 196) (e. g. in Scandinavia, Baden, Bavaria, 
Czechoslovakia), but has not even yet been thoroughly worked out. Heydemann gives useful notes on the larva, 
which are worthy of careful study, although Harrison finds them to be inapplicable to some broods or colonies 
(see Entom., Vol. 66, p. 145 for Harrison's latest contribution). Both authors made repeated experiments. Head 
at first deep black, after the first moult yellowdsh, later mostly very light brownish. Adult larva much more 
variable than that of dilutata ; Heydemann found only ca. 15% really green, ca. 12% more or less spotted with 
purple-brown or chocolate-brown, the spots not so sharply defined as in dilutata, apparently never with 
blackish or clay-coloured tone, the ground-colour itself on the contrary, with an increase of red-brown or purple- 
brown colouring, 30—40% almost entirely light to dark purple-brown, rarely greyish olive-brown, only re¬ 
maining greenish in the segment-incisions and with a brown dorsal line and two distinct whitish subdorsal; the 
best character the very distinct, broadly white (or very light rosy brownish) lateral line. In North Germany, 
christyi seems to be confined to beech; in Durham almost exclusively to wych elm, but in one locality passing 
