MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 
159 ' 
Larva. 
(PI. XX, figs. 1-7.) 
Stretch, 111. Zyg. ainl Bomb. N. Amer., i, p. 116, pi. 10, fig. 9, 1872. 
Lintner, Eiit. Conti*., iv, p. 76, 1878. 
Tepper, Bnll. Brooklyn Eut. Soo., i, p. 3, 1878. 
Goodhue, Can. Ent., xiv, x>* '7'^ 1882. 
Packard, Firth Rep. U. S. Ent. Coinin., lu.s. luj. Forest Trees, p. 455, 1890. 
(rig.) 
Proc. Bost. Soc. Nat. Hist., xxiv, x)p. 522-523, 1890. (Stage III-V.) 
Joiirn. X'. York. Ent. Soc., i, pp. 63-68, 1893. 
Pyar, Psyche, vi, pp. 194-196, Hec., 1891. 
Psyche, vi, pp. 351-353, X'ov., 1892. (Description in full of egg and of the five larval stages of var. 
poritandia.) 
Moth, — Thorax and head cinereous; the tuft on the patagia or shoulder tippets tipped with 
dark brown. Fore wings rounded and somewhat produced toward the apex; of a delicate frosty 
white and brown. Along' the ends of the subcostal A enules of the fore wings arc long strcak.s of 
brown; in the apical and subapical spaces are two long, longitudinal, broad streaks, oblique and 
parallel to the costa, ivliich terminate Just below the apex; middle of the wing white. A long, 
broad line extends from the base to just above the inner angle on the outer margin, lined below 
with white, and deflected upward along the outer edge. Tuft cinereous. IJeneath, cinereous, 
costa darker. Tlie female darker than the male. Hind wings white, the region of the internal 
angle and tuft dark browii. Legs and abdomen cinereous. 
Four examiilesTrom Colorado are slightly darker and less fulvous than in Wisconsin and F'ew 
England individuals. 
A S ? from Franconia, iN". H., received from Mrs. Slosson, is very large, expanding GO mm. 
It has more dark bx'own on the fore wings than usual, a large costo-apical dark brown patch 
containing a white slash and a large wide brown region on the internal edge, extending nj) the 
outer edge to near the apex, the ends of the independent and cubital venules white; but it is not 
nearly so dark in the middle of the wing as in xnr, portlandia. 
The imago of Stretch's caU/orn ica doe.s not seem to diflcr from the Eastern form, and by Messrs. 
Lintiier and Dyar it is regarded as cospecilic with the Eastern form. In respect to jjorilandia^ 
1 also regard this as only a climatic, melanotic variety of the Californian and Eastern dimidiata. 
1 am indebted to Mr. Dyar for a specimen, though it is somewhat rubbed. 
The Oregon form is much darker and slightly larger than the Eastern form, and thus 
conforms to the law in geographical distribution which obtains in the Geometrids, that on the 
Pacific Coast, where the climate is humid, there is a tendency to greater size and darker, almost 
melauistic coloration. Yar. portlandia is a melanotic form, and is dark mouse or sable-brown. 
The fore wings are marked precisely as in the normal forms, bat the brown marks and slashes are 
blacker, and the ground color of the wings smoky or dusky, not being frosted with white scales. 
Hind wings dark mouse color on the inner edge, forming a broad band, extending to the heavy 
dark patch at the inner angle, while the rest of the wing is sordid or smoky white, not frosty 
white. While the length of the fore wing of my type from JMaiue is mm., that of imdlandia 
is 20 mm., the entire expanse being ol mm. 
1 find that the venation of portlandia does not difler from that of the Eastern dimidiata, 
Mr. Lintuer gives at length his reasons for regarding our dimidiata {rimosa) as cospecilic with 
the European dietcea. Specimens were sent by Mr. von Meske to Dr. Speyer, who did not doubt 
that the two sxiecies were identical, the difterence being very slight. lie also gives at length the 
results of his own eomparksons. He likewise refers'to the lact, which I have verified, that there 
are two forms of the larva, both in Europe and in the United States, botlx on the Atlantic and 
Pacific coasts, one being without and the other with a yellow lateral stri])e. 1 slionld not hesitate 
to regard the species as common both to Europe and America, were it not that the European 
species is without a horn. 
In the figures of the British larva of dictwa in Buckler’s work, published by the Ray Society, 
(his fig. 1&, PI. XXXY) the stripe is present on the eighth abdominal segment, while the large horn 
of our form is represeuted by only a hump. In one of Buckler’s figures the hump of the green 
