MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 159 



Larva. 



(PI. XX, figs. 1-7.) 



Stretch, 111. Zyg. aiul Bomb. N. Amer., 1, p. 110, pi. 10, tig. 9, 1872. 



Lintnri; Eut. Coiilr., i\', p. 70, 1878. 



Tei>2)er, Bnll. Brooklyu Eut. Soo., i, p. 3, 1878. 



Goodhue, Can. Eiit., xiv, p. 78, 1882. 



I'aclard, EiftU Rep. U. S. Eut. Comiu., lus. Inj. Forest Trees, p. 455, 1890. (Fig.) 



Proc. Bust. Soc. Nat. Hist., xxiv, pp. 522-523, 1890. (Stage lU-V.) 



.fourn. N. York. Eut. Soc, i, pp. 03-08, 1893. 

 Dyar, Psyche, vi, pp. 191-190, Dec., 1891. 



Psycbe, vi, pp. 351-353, Nov., 1892. (Description in full of egg auil of the live larval stages of var. 



2)ortlaiictla.) 



Moth. — Thorax and head cineieou.s; the tuft on the patagia or shoukler tippets tipped with 

 dark brown. Fore wings rounded aud somewhat produced toward the apex; of a delicate frosty 

 white aud browu. Ak^ng the ends of the subco.stal venules of the fore wings are long streaks of 

 brown; in the apical and subapical .spaces are two long, longitudinal, broad streaks, oblique and 

 parallel to the costa, which 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, aud deflected upward along the outer edge. Tuft cinereous. Beneath, cinereous, 

 costa darker. The female darker than the male. Hind wings white, the region of the internal 

 angle and tuft dark browu. Legs aud abdomen cinereous. 



Four examples from Colorado are slightly darker aud less fulvous than in Wisconsin aud New 

 England individuals. 



AS ? from Francouin, N. H., received from Mrs. Slosson, is very large, expanding GO mm. 

 It has more dark brown on the fore wings than usual, a lai-ge costo-apical dark brown jiatch 

 contaiuing a white slash and a large wide brown region on the internal edge, extending up 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 \ar. j^ortlandki. 



The imago of Stretch's ert7i/br;;8Cff. does not seem to differ from the Eastern form, aud by Messrs. 

 Liutner and Dyar it is regarded as cospecitic with the Eastern form. In respect to P. portlandia., 

 I also regard this as only a climatic, melanotic variety of the Califoruiau and Eastern dimidiata. 

 I am indebted to Mr. Dyar for a specimen, though it is somewhat rubbed. 



The Oregon form is much darker aud slightly larger than the Eastern form, and thus 

 conforms to the law iu geograjihical distribution which obtains in the Geometrids, that ou the 

 Pacific Coast, where the climate is humid, there is a tendency to greater size and darker, almost 

 melanistic coloration. Var. portlandia is a melanotic form, aud is dark mouse or sable-brown. 

 The fore wings are mai'ked precisely as iu the normal forms, but 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 Maine is 25 mm., thaX of imrtlundia 

 is 26 mm., the entire expanse being 54 mm. 



I find that the venation of porthoidia does not differ from that of the Eastern dhmdiatn. 



Mr. Liutner gives at length his reasons for regarding our diinidiata (rimona) as cospecific with 

 the European dicUea. Specimens were sent by Mr. von Meske to Dr. Speyer, who did not doubt 

 that the two species were identical, the difterence being very slight. He also gives at length the 

 results of his own comparisons. He likewise refers to the fact, which I have verified, that there 

 are two forms of the larva, both iu Europe and in the United States, both on the Atlantic and 

 Pacific coasts, one being without and the other with a yellow lateral stripe. I should not hesitate 

 to regard the species as commou both to Europe aud America, were it not that the European 

 species is without a horn. 



Iu the figures of the British larva of dictcva iu Buckler's work, published b^' the Kay Society, 

 (his fig. 16, PI. XXXV) the stripe is present on the eighth abdominal segment, while the large horn 

 of our form is represented by only a hump. In one of Buckler's figures the hump of the green 



